Game casserole almost cooked (8)
I believe the answer is:
lacrosse
'game' is the definition.
(lacrosse is a sport)
'casserole almost cooked' is the wordplay.
'almost' means to remove the last letter (almost the whole word is kept).
'cooked' is an anagram indicator (letters cooked into a new form).
'casserole' with its final letter removed is 'casserol'.
'casserol' is an anagram of 'LACROSSE'.
(Other definitions for lacrosse that I've seen before include "Score's uncertain after the Spanish" , "Ball game using netted stick" , "Game played with a netted stick" , "Game played with nets on sticks" , "Like thirteen of the other clues in the French" .)