The church welcomes lists to purge (7)
I believe the answer is:
cleanse
'purge' is the definition.
(I've seen this before)
'the church welcomes lists' is the wordplay.
'the church' becomes 'ce' (abbreviation for Church of England).
'welcomes' means one lot of letters goes inside another (in sense of 'invites in').
'lists' becomes 'leans' (I've seen this in other clues).
'ce' enclosing 'leans' is 'CLEANSE'.
'to' acts as a link.
(Other definitions for cleanse that I've seen before include "subject to purification" , "purify from sin" , "Make pure" , "Disinfect" , "Bathe" .)