Remaining American's in for it in team (6)
I believe the answer is:
unused
'remaining' is the definition.
(I've seen this before)
'american's in for it in team' is the wordplay.
'american' becomes 'us' (abbreviation for United States).
'in for' is an insertion indicator.
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'in' indicates putting letters inside.
'team' becomes 'und' (I am not sure about this - if you are sure you should believe this answer much more).
'e' inserted within 'und' is 'uned'.
'us' inserted inside 'uned' is 'UNUSED'.
Can you help me to learn more?
(Other definitions for unused that I've seen before include "Neither employed nor second-hand" , "Extra" , "'Fresh, new (6)'" , "Pristine" , "Not utilised" .)