Correspond after start of wedding ceremony (5)
I believe the answer is:
write
'correspond' is the definition.
(writing is a kind of corresponding)
'after start of wedding ceremony' is the wordplay.
'after' is a charade indicator (letters next to each other).
'start of' suggests taking the first letters.
'ceremony' becomes 'rite' (rite is a kind of ceremony).
The first letter of 'wedding' is 'w'.
'w' put next to 'rite' is 'WRITE'.
(Other definitions for write that I've seen before include "Create (manuscript)" , "Draft" , "Jot" , "what an author must do" , "Put down in black and white" .)