Soon minister in cathedral will get caught out (4)
I believe the answer is:
anon
'soon' is the definition.
(synonyms)
I can't explain the remainder of the clue.
(Other definitions for anon that I've seen before include "Mystery writer" , "Nameless (abbr.); soon" , "Presently - or unknown" , "before long" , "Soon - unknown author (abbr)" .)