1. Small bit, in Bogotá → POCO
2. Windows alternative → UNIX
3. Something you have trouble putting down → PAGETURNER
4. Gradually introduce, with "in" → PHASE
5. The Beatles' "___ Blues" → YER
6. Varieties of this include chocolate and yellow → LAB
7. "Then again ...," to a texter → OTOH
8. Puzzles → VEXES
9. Build → ERECT
10. Footwear that lacks defined heels → TUBESOCKS
11. An "A" in geometry → AREA
12. Dull → BLAH
13. Often-redacted fig. → SSN
17. Item that someone with cold feet might have → SKI
21. Verb that fills in the blanks of its own synonym: _ _AR_ → YEN
23. Be just chillin' → LOAF
24. Vividly shocking → LURID
26. Kind of fever → CABIN
27. Ballade or étude → PIECE
29. Analogy words → ISTO
31. Raccoon, humorously → TRASHPANDA
32. It's bubbling below the surface → MAGMA
33. Pointers for some fighters? → EPEES
35. Rom-com plot points → MEETCUTES
36. Channel offering deals → HSN
37. There are more than 2.3 million in N.Y.C.: Abbr. → APTS
38. Industrial cutter → LASER
41. Oscar winner Blanchett → CATE
45. Shady, in modern parlance → SUS
49. Flat hat → TAM
50. Elba who portrayed Nelson Mandela → IDRIS
51. "Some ___!" → NERVE
53. Shenanigan → ANTIC
54. Java ingredient? → CODE
55. Listing on a jobs website → ROLE
56. Losing effort → DIET
58. Wilde thing → POEM
59. Cashless transaction → SWAP
60. Ad or show follower → BIZ
62. African grazer → GNU
63. Challenge from a hard-hit ground ball, perhaps → HOP