Incidental remark made by a team (5)
I believe the answer is:
aside
'incidental remark' is the definition.
(I've seen this before)
'by a team' is the wordplay.
'by' means one lot of letters go next to another.
'team' becomes 'side' (both can mean a sports team).
'a'+'side' is 'ASIDE'.
'made' acts as a link.
(Other definitions for aside that I've seen before include "(Pushed) out of the way" , "Line spoken to theatre audience" , "Line spoken to the audience of a play" , "Out of other people's hearing" , "I.e. sad (anag.)" .)