Fine, long-established congregation (4)
I believe the answer is:
fold
'congregation' is the definition.
(as in welcoming someone into 'the fold')
'fine long-established' is the wordplay.
'fine' becomes 'f' (abbreviation).
'long established' becomes 'old' (I've seen this in another clue).
'f'+'old'='FOLD'
(Other definitions for fold that I've seen before include "Cease trading" , "Gather < church" , "close" , "Small pen for sheep" , "Tuck - pen" .)