Quiet game starting to get gesture of indifference (5)
I believe the answer is:
shrug
'gesture of indifference' is the definition.
(a shrug indicates a lack of interest)
'quiet game starting to get' is the wordplay.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'game' becomes 'RU' (rugby union).
'starting to' suggests taking the first letters.
The first letter of 'get' is 'g'.
'sh'+'ru'+'g'='SHRUG'
(Other definitions for shrug that I've seen before include "Body language indicating indifference or resignation" , "Sign of indifference" , "Express silent doubt" , "Gesture of resignation" , "women's wear" .)