Theme: Tasty - The word SWEET may be placed in front of the last word of the four theme entries to create a new phrase.
20A. Hopes that weren't meant to be : BROKEN DREAMS. Sweet Dreams, a song by Jewel Clip.(4:59)
31A. Concern before changing lanes : BLIND SPOT. Sweet spot, often spoken of as the best place on bat, club, racket, etc. to strike a ball.
40A. Locker room motivator : PEP TALK. Sweet talk, Sweet Nothin's by Brenda Lee Clip.(2:30)
49A. Kids' game with a quickly passed object : HOT POTATO. Sweet potato, may not have another one until next Thanksgiving.
56A. Jackie Gleason catchphrase, and a hint to the ends of 20-, 31-, 40- and 49-Across : "HOW SWEET IT IS!"
Argyle here. Interesting. Nice triple columns on either side. Seareeferd will be happy there is less foreign words today.
Across:
1. Run-down area : SLUM
5. French message-carrying boat : AVISO. We've seen this before.
10. Castle trench : MOAT
14. __ Cod : CAPE
15. Toy blocks : LEGOs
16. "Bus Stop" dramatist : INGE. The 1956 film is only loosely based upon the play.
17. Military assistant : AIDE. (aide-de-camp)
18. Many, many centuries : AEONs
19. In a little while : SOON
23. Jacob's twin : ESAU
24. Dethrones : OUSTs
28. One of Scrooge's four visitors : GHOST
35. Predatory bird : RAPTOR
37. College URL ending : .EDU
38. Nautical opening? : AERO
39. Bird: Pref. : AVI
43. Be in the wrong : ERR
44. __ de soie: silk cloth : PEAU. (literally: skin(pelt) of silk)
46. PBS underwriter : NEA. (Public Broadcasting Service/National Endowment for the Arts)
47. Lassie chaser : LADDIE
52. Goads : PRODS
53. PGA great Sam : SNEAD
54. "__ Grit": John Wayne classic : TRUE
63. Service station job : LUBE
66. Dressy footwear : HEELS
67. Partner of Roy or Chip : DALE. 'Queen of the West' and Chip'n'Dale, Disney chipmunks.
68. Swedish furniture giant : IKEA
69. Lift up : EXALT
70. Ultimatum ending : ELSE
71. Property document : DEED
72. Greenhorns : TYROs
73. In fighting trim : LEAN
Down:
1. Union underminer : SCAB
2. Hibernation site : LAIR
3. Fancy hairstyle : UPDO
4. Most submissive : MEEKEST
5. Ex of Rod Stewart : ALANA
6. Beetle with four wheels, slangily : VEEDUB. (VW,shortened)
7. Movie lab helper : IGOR. Bit of misdirection.
8. Sound measure : SONE
9. Mount near Olympus : OSSA
10. Pageant title since 1952 : MISS USA. Miss Connecticut Erin Brady.
11. Singer Yoko : ONO
12. Gone by : AGO
13. Low card in a royal flush : TEN. An ace-high straight flush is the highest-ranking standard poker hand.
21. Prevent legally : ESTOP
22. Trendy, '60s-style : MOD
25. Muscle beach swimwear : SPEEDO
26. Steaming hot : TORRID. Coincidence it follows the above; I think not.
27. Retail outlets : STOREs
28. Board meeting displays : GRAPHs
29. Be dressed in : HAVE ON
30. Sleep-inducing drug : OPIATE
32. Put on the attack : LET AT
33. Actress Lupino : IDA
34. Void partner : NULL
36. Apartment payment : RENT
41. Veggie on a vine : PEA
42. Shot, as an engine : KAPUT
45. In front : UP AHEAD
48. Hanukkah spinning toy : DREIDEL
50. "Star Trek: Deep Space Nine" constable : ODO. Odo and Quark
51. Verdi opera based on a Shakespeare play : OTELLO
55. Enjoys a siesta : RESTS
57. Sharpen : WHET
58. Like centerfolds : SEXY
59. Be dressed in : WEAR
60. Story : TALE
61. Ingrid's "Casablanca" role : ILSA
62. Espied : SEEN
63. Hinged cover : LID
64. Don Ho's strings : UKE
65. Bonnet-dwelling insect? : BEE
Argyle