Some of the cheap seats in church (4)
I believe the answer is:
apse
'in church' is the definition.
(I've seen this before)
'some of the cheap seats' is the wordplay.
'some of' indicates the answer is hidden within the clue.
'APSE' is hidden within 'cheap seats'.
(Other definitions for apse that I've seen before include "space for altar" , "may be seen in church!" , "Projection to the east end of a church" , "Where you could find a magistrate's chair" , "inside church?" .)