Prevail — rejoice (7)
I believe the answer is:
triumph
I believe this clue is a double definition.
'prevail' is the first definition.
(synonyms)
'rejoice' is the second definition.
(synonyms)
(Other definitions for triumph that I've seen before include "Exult in victory" , "Be victorious" , "celebrate victory" , "Conquer, prevail" , "Prove superior" .)