Remarks we're not supposed to hear as the team comes in (6)
I believe the answer is:
asides
'remarks' is the definition.
(I have seen 'Incidental remarks' mean 'asides' so perhaps 'remarks' could also mean 'asides')
'as the team comes in' is the wordplay.
'the team' becomes 'side' (both can mean a sports team).
'comes in' indicates putting letters inside.
'as' enclosing 'side' is 'ASIDES'.
'we're not supposed to hear' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for asides that I've seen before include "Words spoken on stage" , "Stage whispers" , "confidences passed on to spectators by players" , "Stage-whispers" , "Players aren't meant to hear these" .)