Theme: "Floss" (F-loss). F sound is dropped from the start of one word in each theme entry.
23A. Perfect apartment deal? : GOLDEN LEASE. Golden Fleece. For Jason and the Argonauts.
25A. Saying "Break a leg," say? : STAGE RITE. Stage fright.
46A. Plumbing school basic? : WRENCH LESSON. French lesson for Splynter.
71A. Traditional wisdom about hustlers? : DANCE LORE. Dance floor.
95A. Astronomers' monthly reading? : ORBS MAGAZINE. Forbes magazine.
119A. Song about a yellow ribbon? : OAK BALLAD. Folk ballad.
123A. Hooting, mostly? : OWL LANGUAGE. Foul language.
35D. Supply at the thermometer factory? : READY MERCURY. Freddie Mercury.
40D. Beet-flavored drink? : ROOT COCKTAIL. Fruit cocktail.
What a great title. I recall kicking around a "Drop the f-bomb" idea with Don G ages ago.
All theme entries go through spelling changes. Very consistent. Kathleen dropped three F sound from the last word, 6 from the first word. No odd man out.
1. Some "No Passing" road sections : ESSES
6. Journalist Roberts : COKIE
11. Tests with printed patterns, briefly : ECGs. Had to wait for the C as I just could not nail CATTY (12D. Showing one's claws, so to speak).
15. "Phooey!" : DANG. And 34. "Phooey!" : NERTS
19. 1814 treaty site : GHENT. Treaty of Ghent.
20. Dadaism pioneer : ERNST (Max)
21. Worn item that actually originated in Ecuador : PANAMA HAT. I'd have chickened out and broke this answer and LIE AROUND (125A. Relax) into two entries.
26. "TMI!" : SPARE ME
27. __ Authority : PORT
29. Minor adjustment : TWEAK. Rich often tweaks 50% of the clues. I fare slightly better on Sundays. But totally suck on Mondays/Tuesdays.
30. Descendant of Sperry Rand : UNISYS. Unknown trivia to me.
32. Likely to pry : NOSY
38. Traditionally red structure : BARN
41. Roller with leaves : TEA CART. Tea leaves.
43. Situation of intense scrutiny : HOT SEAT
45. Preview to a view, for short : IMO. Tricky clue.
49. Islands staple : TARO
50. "__ here!" : LOOKEE
52. Glide on powder : SKI. Did not think of snow.
53. Portent : OMEN
55. N.L. lineup absentees : DHs. Also 74A. Ernie Banks epithet : MR. CUB And 17D. 2015 N.L. MVP Bryce Harper, e.g. : NAT
56. Highly values : ESTEEMS
58. The 114th began in 2015 : CONGRESS. So the Supreme Court is older than Congress?
62. "Roundabout" rockers : YES. Unfamiliar with the band or the song.
63. Flip over : CAPSIZE
66. It has all five black keys in its scale : D FLAT. Got via crosses.
67. Singer Mann : AIMEE
69. Black, in verse : EBON
73. Go like hotcakes : SELL
76. Karnak's country : EGYPT
77. "Please help me out" : BE A DEAR
80. Sound of fear : EEK
81. Sunday dinner entrée : RIB ROAST. We don't have a traditional Sunday dinner. How about your family?
84. Little shooter : MINICAM. Great clue.
87. Traitor : RAT
88. Scottish hillside : BRAE
89. Lager alternative : ALE
92. Working : ON DUTY
93. Top-billed : STAR
100. CD-__ : ROM
101. Canton natives : OHIOANS. I always think of Guangzhou when I see "Canton".
103. Key part of Bruce Wayne's wardrobe : BATSUIT
104. 10001 letters : NY NY. Zip code.
105. "M.O." rapper : NELLY
106. Many a reception : GALA
107. Emulate Cher in the '70s : GO SOLO. Also 130. Cher's former partner : SONNY
110. __ law : LEASH
113. Valley where David fought Goliath : ELAH. Valley of Elah.
115. Came out : EMERGED
126. Backs (away) : SHIES
127. Ottoman Empire founder : OSMAN
128. Banned apple spray : ALAR. And 122D. Banned bug spray : DDT
129. Part of Q.E.D. : ERAT
131. Storage facilities : SHEDS
1. They're usually broken before use : EGGS. Also got via crosses. D'oh!
2. Mom-and-pop enterprise : SHOP
3. Ward of Hollywood : SELA
4. Evasive strategy : END RUN
5. Dutchman who painted "The Surprise" : STEEN. Can you link "The Surprise" painting for me?
6. Frozen pizza brand : CELESTE
7. Rock to refine : ORE
8. Hiker's burden : KNAPSACK
9. Schoolyard retort : IS SO
10. Infinite : ETERNAL
11. Some 45-rpm records : EPs
13. Nibble : GNAW
14. Wise one : SAGE
15. Most gloomy : DARKEST. Don't lose hope.
16. Sushi fish : AHI. Not our regular EEL.
18. Old AT&T rival : GTE
22. Was serious about : MEANT
24. Abbr. for people with only two names : NMI. I don't have middle name.
28. Raced : TORE
31. Desires : YENS
33. Rd. atlas listings : STS
36. Chapel Hill athlete : TAR HEEL
37. Eponymous Fox weekly news show : STOSSEL (John). Never watched his show.
38. Anger : BILE
39. Biblical prophet : AMOS
42. Stylish : CHIC
43. Betting favorite, often : HOME TEAM
44. People : ONES
46. Cry : WEEP
47. Radiation units : REMs. Learned from doing xwords. Never know what it stands for.
48. Like a June day, to Lowell : SO RARE
51. Reeves of "John Wick" : KEANU
54. Codebreaker's org. : NSA
57. "May I approach" court conferences : SIDEBARS. Tiny BAR dupe with ROLLBAR (94. Racecar safety feature)
59. "Awake and Sing!" dramatist : ODETS (Clifford)
60. Patriots' org. : NFL
61. Goo amount : GLOB
64. Croatian capital : ZAGREB. Tinbeni's old haunt.
65. Companion of Ares : ENYO. I forgot. We had this sometime ago.
68. "Again ... " : I SAID
69. "Nature" author : EMERSON
70. Live partner : BREATHE. Live and breathe.
72. Tax season VIP : CPA
75. "I need a short break" : BRB (Be Right Back)
78. Belmonts frontman : DION
79. Kin of -trix : ENNE. Or ETTE.
82. Golfer's choice : IRON
83. Luggage danglers : TAGS
85. Loads : A TON. Not A LOT.
86. "Goodness!" : MY MY. And 117. "Goodness!" : EGAD
90. Texas Air Force base : LAUGHLIN. Well, gimme for D-Otto and Anon-T. Unknown to me.
91. He played Emile in Broadway's "South Pacific" : EZIO (Pinza). I only watched the movie "South Pacific". I talk like Bloody Mary.
96. Agcy. that aids start-ups : SBA
97. Guy : MALE
98. Stumped : AT A LOSS
99. "Piece of cake" : IT'S EASY
102. Annually : A YEAR. A partial.
104. "I have time" : NO RUSH
106. Togo neighbor : GHANA
108. Every, in an Rx : OMN. I won't dare to put this or TER in a grid. Rich just told me he would not allow DAMN any more.
109. The 5,922 of a Taj Mahal model : LEGOS
111. Natural balm : ALOE
112. Mark indicating a musical phrase : SLUR
114. Dr. Seuss's "Horton Hears __" : A WHO
116. Phone download : GAME
118. TV sites : DENS
119. Ipanema greeting : OLA
120. Confine to bed, maybe : AIL. Boomer had to take a cane when we walked yesterday. His right hip gave him so much pain. He normally toughs it out the elbow and shoulder pain. This hip pain is something else.
121. Mauna __ : KEA
124. Novelist Deighton : LEN