Theme: Not Quite Black - Five entries whose last word, if placed after the word DARK, form a new phrase.
64A. *When night owls thrive, or where the last words of the starred answers can go : AFTER DARK. (shouldn't have had a star on this clue though.)
17A. *Artsy-sounding microbrew : CRAFT BEER. DARK BEER are usually brewed from a pale malt or lager malt base with a small proportion of darker malt added to achieve the desired shade. Other colourants—such as caramel—are also widely used to darken beers. Very dark beers, such as stout, use dark or patent malts that have been roasted longer. Some have roasted unmalted barley. (as per Wiki, perhaps Lemon can elaborate more fully.)
29A. *Brains, informally : GRAY MATTER. DARK MATTER - "By fitting a theoretical model of the composition of the Universe to the combined set of cosmological observations, scientists have come up with the composition that we described above, ~70% dark energy, ~25% dark matter, ~5% normal matter. What is dark matter?
We are much more certain what dark matter is not than we are what it is." NASA Science
47A. *Officially restricted yet widely known information : OPEN SECRET. DARK SECRET, often proceeded by DEEP; we all have them, eh?
10D. *Many "South Park" jokes : TOILET HUMOR. DARK HUMOR - Humor that is viewed as dark, morbid, cruel, offensive to some, and or graphic in nature and is yet, still found funny. (per Urban Dict.)
25. *Classic Greek ruse : TROJAN HORSE. DARK HORSE - A term used to describe a little-known person or thing that emerges to prominence, especially in a competition of some sort.
Argyle here. I was here yesterday and so were a lot of the answers. Not much excitement so let's get to it.
Across:
1. __ facto : IPSO. (by the fact itself)
5. Cut in stone : ETCH
9. Carell of "The Office" : STEVE
14. Tex-Mex snack : TACO
15. "That's not enough!" : "MORE!"
16. Reason for a skull-and-crossbones warning : TOXIN
19. Spoke (up) : PIPED
20. Sci-fi computer : HAL. From the film, "2001: A Space Odyssey".
21. Crumpled into a ball : WADDED
23. Unhappy times : LOWS
24. Newspaper big shot : EDITOR
26. "Fantastic!" : "SUPER!"
28. Honeybunch : DEAR
34. High-pitched winds : OBOEs
36. "La __": Puccini opera : BOHÈME
37. Muslim pilgrim : HAJJI
40. Spot for a facial : SPA
42. Like pulp magazine details : LURID
43. It's held underwater : BREATH
45. __ salts : EPSOM
49. Gave the go-ahead : OKed
53. Sonnet feature : RHYME
54. Basic chalet style : A-FRAME
56. Cookie used in milkshakes : OREO
58. Security request, briefly : ID CARD
61. DVR button : REC
62. Pitcher Martinez : PEDRO. Retired now, he is an eight-time All-Star, three-time Cy Young Award winner, and 2004 World Series champion.
66. Humiliate : ABASE
67. Sound from Simba : ROAR. The Lion King.
68. Play to __: draw : A TIE
69. "See ya!" : "LATER!"
70. Taxpayer IDs : SSNs
71. Mix : MELD
Down:
1. Bugged, as a bug bite : ITCHED. ???
2. Event with floats : PARADE
3. Justice Antonin : SCALIA
4. Gut-punch response : "OOF!"
5. Ban on trade : EMBARGO
6. See 18-Down : TOED. 18D. With 6-Down, kind of sloth : TWO
7. Believability, to homeys : CRED. Short for "credibility".
8. Joan of Arc's crime : HERESY
9. Sponsor at some NHRA events : STP. National Hot Rod Association (NHRA)
11. Overseas trader : EXPORTER
12. Hillside house asset : VIEW
13. Finales : ENDS
22. Not bright at all : DUMB
27. Renaissance painter Veronese : PAOLO
30. High-__ monitor : RESolution
31. "__ your instructions ..." : AS PER
32. Brit. record label : EMI
33. Lobster color : RED. Not in their natural state.
35. Itsy-__ : BITSY
37. "The Wire" airer : HBO. Central to the structure and plot of the show is the use of electronic surveillance and wiretap technologies by the police—hence the title "The Wire".
38. Dadaist Jean : ARP. Sculptor, painter, poet and abstract artist. Also, frequent crossword visitor.
39. Derided : JEERED AT
41. Orangutan or chimp : APE
44. Prefix with sphere : HEMI
46. Rubberneckers : STARERS
48. Trees used for shingles : CEDARS
50. Discipline with kicks : KARATE
51. "Kick it up a notch!" chef : EMERIL. His site.
52. Floored with a haymaker : DECKED. A haymaker is slang boxing term for a wild swinging punch, using much of the same motion of someone using a scythe, twisting his waist and shoulders round before turning back.
55. Depression era pres. : FDR
56. Down Under gem : OPAL
57. McEntire sitcom : "REBA"
59. Corp. cash mgrs. : CFOs. (chief financial officer)
60. __ earlier time : AT AN
63. Opposite of 'neath : O'ER
65. River blocker : DAM
Argyle