Thanks to everyone who has provided hints to this. Despite the helpful nudges I'm frustratingly stuck on two:
20a - 'Parades starting to suffer on hard earth' (9). I have S?'RE?S.
39a - 'Wanting to have date, gets ready' (7). I have G?RD.
In each case, clues consist of a definition for the answer (number of letters in brackets) and wordplay leading to the entered form (number of letters I've shown).
I also can't parse 36d - I think the grid entry is TOD.
Any help gratefully received! Thanks.