I apologise in advance if this has been previously answered (as per other response).
21 down: Not much pressure for mathematician and philosospher (6) P???A?
24 across: It may detect origin of smoke in church, I hear (6) P???A?
25 down: Note trouble for joiner (4) ??I?
Absolutely stuck on the bottom right hand side of this crossword. Many thanks and if you have an explanation it is very much appreciated.