Gong finally sounded going into lunch? (5)
I believe the answer is:
medal
'gong' is the definition.
(gong can mean a prize or medal)
'finally sounded going into lunch?' is the wordplay.
'finally' suggests the final letters.
'going into' is an insertion indicator.
'lunch?' becomes 'meal' (lunch is a kind of meal).
The last letter of 'sounded' is 'd'.
'd' inserted within 'meal' is 'MEDAL'.
(Other definitions for medal that I've seen before include "Religious or commenorative metal piece" , "Religious or commemorative pin" , "Winner's award" , "Award for service" , "George Cross, for instance" .)