I think these are correct but the parsing eludes me.....
11a. Flipping, flipping short clergyman (3) - REV (Clergyman) - I thought this was 'REVersing' (flipping) shortened , but that doesn't explain why 'Flipping' appears twice, so I'm obviously missing something.
20d. Eastern port making grandad queen then? (7) - NANKING (Eastern Port) - It looks like 'Grandad' becomes NAN and 'Queen' becomes king, but I can't see the instruction to switch them - or, I could be comlpletly wrong.