Disagree with Charlie over a game of cricket (7)
I believe the answer is:
contest
'disagree' is the definition.
(thesaurus)
'with charlie over a game of cricket' is the wordplay.
'with' is a charade indicator (letters next to each other).
'charlie' becomes 'c' (phonetic alphabet: alpha, bravo, charlie etc.).
'over' becomes 'on' (I've seen this in other clues**).
'a game of cricket' becomes 'test'.
'c' put next to 'on' is 'con'.
'con'+'test'='CONTEST'
(Other definitions for contest that I've seen before include "Tournament" , "Competition or conflict" , "Oppose - competition" , "Match" , "Competition; dispute" .)