Everybody in church retains a friendly relationship (8)
I believe the answer is:
alliance
'friendly relationship' is the definition.
'everybody in church retains a' is the wordplay.
'everybody' becomes 'all' (I've seen this before).
'church' becomes 'CE' (abbreviation for Church of England).
'retains' is an insertion indicator.
'in'+'ce'='ince'
'ince' placed around 'a' is 'iance'.
'all'+'iance'='ALLIANCE'
(Other definitions for alliance that I've seen before include "Association for mutual benefit" , "Union, association" , "Confederation" , "Group acting together for common cause" , "Wanting marriage" .)