New compiler? I found it very difficult, anyway, and there are three left I'm not sure about. Any hints, please?
8a Once upon a time some surgery (4)
A?O?
No idea of anything that parses
21a Noisy little thing about to trap one hound (6)
?I?I?A
I'm fairly sure of the answer to this, but "hound" doesn't look right
17d Shoot round exceptional bird (7)
?U?T?R?
I can think of two birds that fit, but neither seems to parse.