Evil trap set up for game (6)
I believe the answer is:
tennis
'evil trap set up for game' is the definition.
(I've seen this before)
'evil trap set up' is the wordplay.
'evil' becomes 'sin' (I've seen this before).
'trap' becomes 'net' (net is a kind of trap).
'set up' says the letters should be written in reverse.
'sin'+'net'='sinnet'
'sinnet' written backwards gives 'TENNIS'.
(Other definitions for tennis that I've seen before include "Game of the Williams sisters and of Roger Federer" , "Sent in, oddly, to play a sport" , "Sent in, strangely, for sport" , "Evil trap set up for game" , "Roger Federer's game - anyone for it?" .)