Theme: Beyond Medium - Well, well, well done.
20A. Position of football lineman J.J. Watt : DEFENSIVE END. End well.
28A. Average, in math : ARITHMETIC MEAN. Mean well.
42A. Fountain treat with Bosco, maybe : CHOCOLATE SHAKE. Shake well.
47A. Echoic remark before "What do we have here?" whose words can follow the ends of 20-, 28- and 42-Across : "WELL WELL WELL"
Argyle here. Argyle here (with a sense of déjà vu).
Author:
1. 24 minutes, in the NBA : HALF
5. Giant among wholesale clubs : SAM'S
9. Heat unit : THERM
14. Rideshare app : UBER
15. __-deucey : ACEY
16. Great Lakes mnemonic : HOMES. Test yourself.
17. Author Wiesel : ELIE
18. Improbable tale : YARN
19. Candy heart message : I LUV U
23. Sound heard by a shepherd : [BAA!]
24. Intense, as a competitor : FIERCE
33. Unsteady on one's feet : AREEL
34. Country rocker Steve : EARLE
35. "__ & the Women": 2000 Gere film : DR. T
36. Divisions of tennis matches : SETs
37. Actress Holmes : KATIE
38. Ticked off : SORE
39. "How was __ know?" : I TO
40. Diamond weight : CARAT
41. Word before Master or case : STAIR
45. Biblical dancer : SALOME
46. For each : PER
54. Many Mideast residents : ARABS
57. Verdi opera set in Egypt : "AIDA"
58. Color similar to turquoise : AQUA
59. '90s candidate Ross : PEROT
60. Hosp. scans : MRIs. (Magnetic Resonance Imaging)
61. Road grooves : RUTS
62. Japanese capital : TOKYO
63. Literary sister of Amy, Meg and Jo : BETH. (Little Women)
64. Magnitude : SIZE
Down:
1. Tinged : HUED
2. Having the skills : ABLE
3. Actor/singer Garrett : LEIF. He became famous in the 1970's as a child actor, pop star and teen idol.
4. They're on the house : FREEBIES
5. Prepares to have one's tongue depressed : SAYS "AH"
6. Healthy berry : ACAI
7. Griffin of game show fame : MERV
8. "Auld Lang __" : SYNE
9. Skating danger : THIN ICE
10. Texas __: poker game : HOLD 'EM
11. Big Australian bird : EMU
12. Gun, as an engine : REV
13. The Spartans of the NCAA : MSU. (Michigan State University)
21. Part of NFL: Abbr. : NATL. (National)
22. TurboTax option : E-FILE
25. Hardwood tree that drops acorns : RED OAK
26. Fisher who plays Princess Leia : CARRIE. Daughter of Debbie Reynolds and Eddie Fisher.
27. Come in : ENTER
28. "Queen of Soul" Franklin : ARETHA
29. Equip anew, as a machine shop : RETOOL
30. Ben Stiller's mom : MEARA. Anne.
31. Really bother : EAT AT
32. Clichéd : TRITE
33. Nike competitor : ASICS
37. Superman's birth name : KAL-EL
38. Sci-fi classic that introduced Princess Leia : "STAR WARS"
40. Regains consciousness : COMES TO
41. Poet Silverstein : SHEL
44. A cannonball makes a big one : SPLASH
48. Shepherd's charge : LAMB
49. Lamp-to-plug line : WIRE
50. Improve text : EDIT
51. Same: Pref. : EQUI
52. Skating jump : LUTZ
53. Cut with light : LASE
54. Fitting : APT
55. Rock's __ Speedwagon : REO
56. Genesis boat : ARK
Argyle