Congregation bent her out of shape, suppressing resistance (8)
I believe the answer is:
brethren
'congregation' is the definition.
(thesaurus)
'bent her out of shape suppressing resistance' is the wordplay.
'out of shape' is an anagram indicator.
'suppressing' is an insertion indicator.
'resistance' becomes 'r' (electronics abbreviation).
'bent'+'her'='benther'
'benther' is an anagram of 'brethen'.
'brethen' enclosing 'r' is 'BRETHREN'.
(Other definitions for brethren that I've seen before include "old relatives?" , "People ordered" , "Biblical or other old brothers" , "Religious group members" , "Fellow Christians or members of a religious order" .)