Prize promoted in feast (5)
I believe the answer is:
revel
'feast' is the definition.
(thesaurus)
'prize promoted' is the wordplay.
'prize' becomes 'lever' (I've seen this before).
'promoted' shows that the letters should be reversed in order (going up, in a down clue).
'lever' backwards is 'REVEL'.
'in' is the link.
(Other definitions for revel that I've seen before include "Make merry, whoop it up" , "Rejoice" , "Have noisy fun" , "Feast riotously" , "Celebrate with a lever, strangely" .)