Long trousers affected Ashe's game (8)
I believe the answer is:
pheasant
'game' is the definition.
'long trousers affected ashe's' is the wordplay.
'long' becomes 'pant' (I've seen this before).
'trousers' indicates putting letters inside (trouser can mean to steal or take).
'affected' is an anagram indicator.
'ashe' with letters rearranged gives 'heas'.
'pant' placed around 'heas' is 'PHEASANT'.
(Other definitions for pheasant that I've seen before include "something to pluck?" , "Colourful game bird" , "Cock" , "Ant heaps (anag.)" , "Game-bird" .)