Before end of game, your ball changed colour (5,4)
I believe the answer is:
royal blue
'colour' is the definition.
(royal blue is a kind of colour)
'before end of game your ball changed' is the wordplay.
'before' is a charade indicator (letters next to each other).
'end of' says to take the final letters.
'changed' is an anagram indicator.
The last letter of 'game' is 'e'.
'your'+'ball'='yourball'
'yourball' is an anagram of 'royalblu'.
'e' put after 'royalblu' is 'ROYAL BLUE'.
(Other definitions for royal blue that I've seen before include "Dark colour" , "A shade Conservative" , "Your be-all (anag) - shade" , "Queen's shade?" , "Bally euro (anag.)" .)