Left area of church to pass into disuse (5)
I believe the answer is:
lapse
'pass into disuse' is the definition.
(I've seen this before)
'left area of church' is the wordplay.
'left' becomes 'l' (common abbreviation).
'area of church' becomes 'apse' (I've seen this before).
'l'+'apse'='LAPSE'
'to' is the link.
(Other definitions for lapse that I've seen before include "Passing - mistake" , "Negligence" , "breach of protocol?" , "unguarded moment" , "Brief failure of judgement" .)