Criminal activity in team work (6,3)
I believe the answer is:
inside job
'criminal activity' is the definition.
(I've seen this before)
'in team work' is the wordplay.
'team' becomes 'side' (both can mean a sports team).
'work' becomes 'job' (job is a kind of work).
'in'+'side'+'job'='INSIDE JOB'
(Other definitions for inside job that I've seen before include "Crime committed by those who knew the place" , "Staff-colluding crime" , "crime of disloyalty" , "doublecrossing crime" , "Crime with collusion" .)