Thanksgiving meal (6)
'thanksgiving meal' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for feast that I've seen before include "Tuck-in; blow-out" , "Lavish spread" , "Saint's day, for example" , "Junket" , "Lavish meal" .)
(Other definitions for turkey that I've seen before include "Mostly Asian country" , "Large farmed bird" , "Bird traditionally eaten on Christmas day" , "sometimes cold" , "A failed play or a seasonal bird" .)