The final answer to this cryptic crossword is the name of a Christmas carol, whose three-word title can be extracted from the letters of the grid. I hope you enjoy!
1 Quote ends up in the Nesbit, Mississippi Republic (4)
3 Boss's travelling between Pennsylvania and Oklahoma identified with old financial record (8)
9 Let it go: O's exhausted from Foster pitching escapade, giving up 6 after the first (3,4)
10 Rolled over and skinned after cleaning pointy instrument (5)
11 School for lad, Yarboro Finishing, to protest over losing second place, in advance (11)
13 At the moment, me, not I, is used incorrectly (2,4)
15 Closer in Golden, CO revival (6)
17 Bachelor debut: nurse, nun scrambling to overcome blonde's lead; European red-head is a source of heat (6,6)
20 Amex transaction offers bonus (5)
21 Clean-cut Partridge Family opener covers Outfield after Weir's last-second cancellation (4,3)
22 Seeing Wounded Knee in a day provides time to relax (8)
23 Location decreasingly used for music club closing down? (4)
1 Sewer crochets eyelet stitches at first, setting up loops (8)
2 Donation to bird rehab returned with neither envelope nor enclosed letter of introduction (5)
4 Mania treated with drug injection results in a lack of vigor (6)
5 Vacuum devices fill small plastic cups with bad pinot and rum; Merry's third is spit out (7,5)
6 Bloom concealed by whorl and ovary (7)
7 Crazy text saying yes includes two emoji hearts (4)
8 Fear losing primary right to life in Mississippi? Perspicacious. This is a sign something is wrong (5,7)
12 Superb rectifier with reduced voltage fluctuation (8)
14 Agent utters wanton nonsense at closing (7)
16 Spread lies about situation, ultimately! (6)
18 English supermodel reflected on initially supporting Bowie's choice of spouse (5)
19 Cat-call disturbs women no end (4)
- Fixed bad positioning of 1 down clue, and added higher resolution image for grid.
- Edited enumeration for 21A. It can work with the previous (7), but (4,3) is likely more natural.
The instructions indicate that the answer can be extracted from the letters in the grid. They do not indicate where the instructions for picking which letters are used come from. This distinction is deliberate and important.