What the bride says afterwards won't be in church (8)
I believe the answer is:
idolater
'what the bride says' is the definition.
I can't judge whether this defines the answer.
'afterwards won't be in church' is the wordplay.
I cannot really see how this works, but
'afterwards' could be 'later' (synonyms) and 'later' is located in the answer.
The remaining letters 'ido' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for idolater that I've seen before include "Tailored for image worshipper" , "devotee" , "great admirer" , "Worshipper of false gods" , "Person who worships graven images" .)