Messenger from wedding cycled round front of church (6)
I believe the answer is:
nuncio
'messenger' is the definition.
(ambassador or messenger for the Catholic Church)
I don't understand how the remainder of the clue works.
(Other definitions for nuncio that I've seen before include "Pope's ambassador" , "Vatican delegate" , "Sent by the Pope" , "Papal envoy" , "Papal messenger" .)