I think these are correct, but having trouble with the parsing. help appreciated....
5a. Amount of medicine doctor's initially expecting to keep the old well (8) - MEGADOSE (Amount of medicine)
14a. Theatre employee finds a celebrity reeling in shock (5,7) - STAGE MANAGER (Theatre employee)
25a. Altogether fair and square at the start (8) - OUTRIGHT (Altogether?)
5d. Not all current No.1's are covered by, say. boy band (7) - MANACLE (Band) - I don't know if it's relevant but the answer to 1a. is THEFTS.
I can see MALE for 'Boy' but not the rest.