Theme: Down by the Sea - The end word of the theme entries relates to water movement.
20A. Chocolate-ribboned ice cream flavor : FUDGE RIPPLE
27A. One setting a new high : RECORD BREAKER. Waves as they break (fall over themselves and crash onto the shore) are known as breakers.
49A. Salon treatment : PERMANENT WAVE
56A. "Nifty, huh?" : "ISN'T IT SWELL?". A wave, especially when long and unbroken; What causes boats to rise and fall out on the ocean.
Argyle here. Too bad Donna couldn't get the entries in order, from slight movement to tsunami.
Across:
1. Shoppers' aids : BAGS
5. Chantilly product : LACE. Let the Big Bopper get your blood going. Clip.(2:27)
9. Religious subgroups : SECTS
14. Kareem's alma mater, briefly : UCLA. Basketball Hall of Famer Abdul-Jabbar played three seasons for the UCLA Bruins from 1966–69. He was known as Lew Alcindor at the time.
15. Airline with famously tight security : EL AL
16. Hackneyed : TRITE
17. Custardy Spanish dessert : FLAN, Image.
18. O'Hara homestead : TARA. Theme from the original soundtrack Clip.(3:51)
19. Nattered away : RAN ON
23. Two-outs-in-a-single-AB stats : DPs. Baseball's double-play.
24. Mai __ : TAI. Cocktail.
25. Asian cat breed : SIAMESE
32. Windsor Castle initials : HRH. His Royal Highness or Her Royal Highness.
33. Fabled fiddler : NERO
34. "All By __": Celine Dion hit : MYSELF. Clip.(3:59)
37. Spread in a dairy case : OLEO
39. Spots on a screen? : ADS. TV screen.
41. Inter or et follower : ALIA
42. Setting where a medium isn't rare : SEANCE
45. Nepal's continent : ASIA
48. Pioneered : LED
52. Aptly named boss at the quarry where Fred Flintstone works : MR. SLATE
54. Livy's "I love" : AMO. Titus Livius (59 BC – AD 17), known as Livy in English, was a Roman historian.
55. Mouse spotter's shriek : "EEK!"
62. Stockpile : AMASS
64. __'acte : ENTR. French for "between the acts", intermission.
65. Thought : IDEA
66. Capone henchman : NITTI. Francesco Raffaele Nittoni, AKA Frank Nitto, AKA Frank 'The Enforcer' Nitti" (January 27, 1881 – March 19, 1943) was a Prohibition gangster in Al Capone's gang.
67. Vaulted cathedral part : APSE
68. Sask. neighbor : N. DAK.
69. Isaac with a bow : STERN. Ukrainian-born violin virtuoso.
70. Inner Hebrides isle : SKYE. Home to Talisker single malt Scotch.
71. "... the slithy toves / Did __ and gimble ...": "Jabberwocky" : GYRE
Down:
