Clergy making fortune in church (5)
I believe the answer is:
cloth
'clergy' is the definition.
(I have seen 'The clergy ' mean 'cloth' so perhaps 'clergy' could also mean 'cloth')
'fortune in church' is the wordplay.
'fortune' becomes 'lot' (as in a person's lot in life).
'in' means one lot of letters goes inside another.
'church' becomes 'ch' (common abbreviation).
'lot' going within 'ch' is 'CLOTH'.
'making' is the link.
(Other definitions for cloth that I've seen before include "Textiles" , "ministers" , "The clergy" , "rag" , "Fabric, textile" .)