Sent in to organise game (6)
I believe the answer is:
tennis
'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' anagrammed gives 'TENNIS'.
(Other definitions for tennis that I've seen before include "court contest" , "Racquet sport" , "Wimbledon sport" , "Sport Dwight Davis gave trophy for" , "Racquet-game" .)