Team member's weapon (7)
I believe the answer is:
sidearm
'weapon' is the definition.
(type of gun)
'team member's' is the wordplay.
'team' becomes 'side' (both can mean a sports team).
'member' becomes 'arm' (member can mean a limb).
'side'+'arm'='SIDEARM'
(Other definitions for sidearm that I've seen before include "weapon" , "Officer may carry this" , "One may be fired" , "Piece" .)