When in church for example (4)
I believe the answer is:
case
'example' is the definition.
(I've seen this in another clue)
'when in church' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'in' is an insertion indicator.
'church' becomes 'ce' (abbreviation for Church of England).
'as' going into 'ce' is 'CASE'.
'for' acts as a link.
(Other definitions for case that I've seen before include "Trunk" , "Item of luggage" , "Judge tries this" , "Piece of luggage and a court proceeding" , "A law suit or a container" .)