Fellow changes seats and eats well (6)
I believe the answer is:
feasts
'eats well' is the definition.
(I've seen this before)
'fellow changes seats' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'changes' indicates an anagram.
'seats' anagrammed gives 'easts'.
'f'+'easts'='FEASTS'
'and' acts as a link.
(Other definitions for feasts that I've seen before include "eats well" , "Banquets and major meals" , "religious celebrations" , "'Ceremonial, elaborate meals (6)'" , "Partakes of a banquet" .)