Clergyman caught on immediately (5)
I believe the answer is:
canon
'clergyman' is the definition.
(I've seen this before)
'caught on immediately' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'on' means one lot of letters go next to another.
'immediately' becomes 'anon' (I've seen this before).
'c'+'anon'='CANON'
(Other definitions for canon that I've seen before include "Part of chapter" , "General principle or kind of clergyman" , "accepted criterion" , "Criterion; church official" , "Body of works" .)