Another pew seating elder initially in part of church (4)
I believe the answer is:
apse
'part of church' is the definition.
('apse' is part of 'church')
'another pew seating elder initially' is the wordplay.
'initially' indicates taking the first letters.
The initial letters of 'another pew seating elder' is 'APSE'.
'in' is the link.
(Other definitions for apse that I've seen before include "Church's part" , "In sacred space" , "Recess in church wall" , "place in church" , "may be seen in church!" .)