Locked up cool team (6)
I believe the answer is:
inside
'locked up' is the definition.
(I've seen this before)
'cool team' is the wordplay.
'cool' becomes 'in' ('in' can mean fashionable or cool).
'team' becomes 'side' (both can mean a sports team).
'in'+'side'='INSIDE'
(Other definitions for inside that I've seen before include "close to centre" , "Middle" , "being held" , "Behind bars (sl.)" , "undercover" .)