Permit husband to leave fungus on church (7)
I believe the answer is:
licence
'permit' is the definition.
(I've seen this before)
'husband to leave fungus on church' is the wordplay.
'husband' becomes 'h'.
'to leave' suggests deleting specific letters.
'fungus' becomes 'lichen' (type of plant comprised of a fungus and alga).
'on' is a charade indicator (letters next to each other).
'church' becomes 'ce' (abbreviation for Church of England).
'lichen' with 'h' taken away is 'licen'.
'licen'+'ce'='LICENCE'
(Other definitions for licence that I've seen before include "Certify" , "Driving permit" , "Grant of permission" , "Freedom of action" , "Self-indulgence; permit" .)