Theme: R&DXTOO - Not Research and Development but 2(too) R's in the first word and 2(too) D's in the second word.
17A. Dangerously sharp : RAZOR-EDGED
22A. "Curb Your Enthusiasm" creator : LARRY DAVID. This guy.
35A. Common pump choice : REGULAR UNLEADED
47A. Gnarly one on the waves : SURFER DUDE
56A. "Star Wars" droid, and a hint to letters shared by 17-, 22-, 35- and 47-Across : ARTOO-DETOO. (phonetically spelling of R2-D2)
Argyle here. Anchored by a grid spanner and some interesting fill; a decent Tuesday.
Across:
1. Lunchbox staple, initially : PBJ. Travels better than BLT.
4. Handy, say : ABLE
8. Hatcher of "Lois & Clark" : TERI
12. Pakistani language : URDU
14. Pakistan neighbor : IRAN
15. Tablecloth fabric : LINEN. Who had to get up because "We need the sheets for the table"?
16. Striped fish : BASS
19. Ranch nightmare : STAMPEDE
21. "Wake Up Little Susie" singer Don or Phil : EVERLY. Phil passed away in January.
24. Next-to-last Greek letter : PSI
26. Difficult turn on the slopes : ESS
27. Fellows : MEN
28. Cape Town's land: Abbr. : RSA. (Republic of South Africa)
31. 1983 Streisand film : "YENTL"
33. "From __ to shining ..." : SEA
34. Has-__ : BEEN
39. Early garden : EDEN
40. La-Z-Boy room : DEN
41. Very unpleasant, weather-wise : NASTY
42. Country south of Turk. : SYR. Turkey/Syria
43. Costly cracker-topper : ROE
44. 35-Across, e.g. : GAS. (35A Common pump choice)
46. Boxer's stat : KOs. (knock out)
50. "Beat it, kid!" : "GO HOME!"
53. "I'm serious!" : "NO, REALLY!". Cute string.
58. Eyelid trouble : STYE
59. Taxi fixture : METER
60. Clothier Strauss : LEVI
61. Traffic sound : HORN
62. Glimpse : ESPY
63. Lose sleep (over) : FRET
64. Mario Brothers console : NES. (Nintendo Entertainment System)
Down:
1. Stout servers : PUBS
2. Unruly kid : BRAT
3. Holden Caulfield creator : J.D. SALINGER. The Catcher in the Rye (1951)
4. Cable stations, e.g. : AIRERs
5. Vintage sitcom stepfamily : BRADYs. The Brady Bunch (TV Series 1969–1974)
6. Vegged out : LAZED
7. Ambient music pioneer Brian : ENO
8. Assisted through a tough time, with "over" : TIDED. Verb phrase: 15. tide over, to assist in getting over a period of difficulty or distress. Dictionary.com
9. Caltech grad, often: Abbr. : ENGR.
10. Hose holder : REEL
11. Race nickname : INDY. (Indianapoli) Big racing news: Dale Earnhardt Jr. wins Daytona 500!
13. West Point letters : USMA. (United States Military Academy)
15. "Deathtrap" playwright Ira : LEVIN
18. Disclose : REVEAL
20. Suave shelfmate : PRELL. Hair care.
23. "So true!" : "AMEN!"
24. Funereal piles : PYREs
25. Like some rye bread : SEEDY
28. Comedian who ended his show with "... and may God bless" : RED SKELTON
29. Make arrangements for : SEE TO
30. Raggedy dolls : ANDYs. (brother to Raggedy Ann)
32. Winery cask : TUN
33. Baltimore daily : SUN
34. Cry from a flock : [BAA!]. A bit down on the farm today. 47D. "Here, piggies!" : "SOOEY!"
36. Loved to pieces : ADORED
37. Scuba spot : REEF
38. Come after : ENSUE
43. Gossip fodder : RUMOR
44. Vinyl record feature : GROOVE
45. Cleverly skillful : ADROIT
48. "It's open!" : "ENTER!"
49. Imprecise cooking measure : DASH
50. Pool or polo : GAME
51. Raw rocks : OREs
52. Web address opening : HTTP
54. Harp kin : LYRE
55. Strong urges : YENS
57. Pixie : ELF
Argyle