I believe the answer is:
'makes merry' is the definition.
('revel' can be a synonym of 'make merry')
This is the entire clue.
(Other definitions for revels that I've seen before include "Our . . . . . . now are ended (The Tempest)" , "Has great fun with levers" , "Parties" , "Celebrations with levers" , "Carousals, high jinks" .)