Attack silence after working game (6)
I believe the answer is:
onrush
'attack' is the definition.
('onrush' can be a synonym of 'attack')
'silence after working game' is the wordplay.
'silence' becomes 'sh' (I've seen this in other clues).
'after' says to put letters next to each other.
'working' becomes 'on'.
'game' becomes 'ru' (rugby union).
'on'+'ru'='onru'
'sh' put after 'onru' is 'ONRUSH'.
(Other definitions for onrush that I've seen before include "sudden swoop" , "Forceful forward flow" , "Career" , "Swarm" , "Stampede" .)