Fellow, ancient, seeing wrinkle (4)
I believe the answer is:
fold
'wrinkle' is the definition.
(thesaurus)
'fellow ancient' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'ancient' becomes 'old' ('old' can be similar in meaning to 'ancient').
'f'+'old'='FOLD'
'seeing' acts as a link.
(Other definitions for fold that I've seen before include "Congregation; (firm) go bankrupt" , "enclosure" , "Crease" , "Sheep pen; disintegrate" , "Collapse; bend in half" .)