For every church has a seat (5)
I believe the answer is:
perch
'a seat' is the definition.
(perch is a kind of seat)
'for every church' is the wordplay.
'for every' becomes 'per' (I've seen this before).
'church' becomes 'ch' (common abbreviation).
'per'+'ch'='PERCH'
'has' is the link.
(Other definitions for perch that I've seen before include "Fish and imperial measure" , "Freshwater fish - roost" , "A fish; alighting place" , "Rest (as a bird)" , "pew?" .)