Ah Enigmatist, we meet again. And once again you've put me in a bad mood. Having spent an hour jamming words into the grid based on what fitted, rather than understanding any clues (well OK, a couple...
17a Retired wimps fret (4) H---
20d Have multiple offspring to argue greatly over (6)
21a Unexpectedly sing Moon River for somebody in church (9) M-----N--
Muchas gracias...