Sent in to organise the game (6)
I believe the answer is:
tennis
'the game' is the definition.
(tennis is a kind of game)
'sent in to organise' is the wordplay.
'to organise' indicates an anagram (I've seen 'organising' mean this).
'sent'+'in'='sentin'
'sentin' is an anagram of 'TENNIS'.
(Other definitions for tennis that I've seen before include "Sport Dwight Davis gave trophy for" , "Sent in, strangely, for sport" , "Game played with racquets" , "Sent in to play the game, oddly" , "Racket sport" .)