Congregation is female and not young (4)
I believe the answer is:
fold
'congregation' is the definition.
(I've seen this before)
'female and not young' is the wordplay.
'female' becomes 'f' (abbreviation).
'and' says to put letters next to each other.
'not young' becomes 'old' ('old' is the opposite to 'young').
'f'+'old'='FOLD'
'is' is the link.
(Other definitions for fold that I've seen before include "Church following" , "stop functioning" , "Members of church" , "Prepare pages to put in small envelope" , "Tuck - pen" .)