Use coin to decide a team reject (4,5)

'use coin' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.

'to decide a team reject' is the wordplay.
I cannot really see how this works, but
'to' is found in the answer.
'a' is within the answer.
'team' could be 'side' (both can mean a sports team) and 'side' is found in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?