Stuck on the last four:
23A Plant that favours much of 15 (5) - ??U?E
25A Otter near stream? (7) - ????T?T
16D Thole (6) - ?C?E?? - Might be ACCEED. I know a thole pin as the pivot for an oar in a skiff, but I don't think that is meant here.
20D Come again? (5) - R???? - Might be RERUN
If it helps, I have ACCOUNT for:
15D Database (7) - A?C????
... and the 5th and 7th letters of that answer are the 3rd and 5th letters of 23A & 25A respectively.