Monk left Church backed into subterfuge (7)
I believe the answer is:
recluse
'monk' is the definition.
(thesaurus)
'left church backed into subterfuge' is the wordplay.
'left' becomes 'l' (common abbreviation**).
'church' becomes 'ce' (abbreviation for Church of England).
'backed' says the letters should be written backwards.
'into' means one lot of letters goes inside another.
'subterfuge' becomes 'ruse' (I've seen this before).
'l'+'ce'='lce'
'lce' backwards is 'ecl'.
'ecl' put within 'ruse' is 'RECLUSE'.
(Other definitions for recluse that I've seen before include "one stays away from people" , "Solitary figure" , "One lives in solitude" , "Person who lives alone and avoids others" , "Person who lives alone and avoids people" .)