Team has left something in the playground (5)
I believe the answer is:
slide
'in the playground' is the definition.
('slide' is part of 'playground')
'team has left' is the wordplay.
'team' becomes 'side' (both can mean a sports team).
'has' means one lot of letters goes inside another.
'left' becomes 'l' (common abbreviation).
'side' enclosing 'l' is 'SLIDE'.
'something' is the link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for slide that I've seen before include "Picture" , "Idles about on children's chute" , "Drop" , "Decline" , "Slip, slither, skid" .)