Cupola is lead covering part of church (5)
I believe the answer is:
aisle
'part of church' is the definition.
(I've seen this before)
'cupola is lead covering' is the wordplay.
'covering' indicates a hidden word.
'AISLE' can be found hidden inside 'cupola is lead'.
(Other definitions for aisle that I've seen before include "Way between seats" , "Walkway between seats" , "way for prospective union members?" , "lateral strip" , "Divide in a church" .)