European beer knocked back in feast (6)
I believe the answer is:
regale
'feast' is the definition.
(thesaurus)
'european beer knocked back' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'beer' becomes 'lager' (lager is a kind of beer).
'knocked back' is a reversal indicator.
'e'+'lager'='elager'
'elager' back-to-front is 'REGALE'.
'in' acts as a link.
(Other definitions for regale that I've seen before include "Ply" , "Entertain with conversation" , "Shower" , "Entertain royally" , "Supply copiously" .)