A gong (5)
I believe the answer is:
medal
'a gong' is the definition.
(gong can mean a prize or medal)
This is all the clue.
(Other definitions for medal that I've seen before include "Religious or commenorative metal piece" , "Award for bravery etc" , "George Cross, for instance" , "Gong (sl.)" , "Religious or commemorative pin" .)