Be jubilant (5)
I believe the answer is:
exult
'be jubilant' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for exult that I've seen before include "Show triumphant joy" , "Show triumphant elation" , "Rejoice intensely" , "Crow in triumph" , "Feel or express triumph" .)