Negative aspect of losing team (8)
I believe the answer is:
downside
'negative aspect' is the definition.
(I've seen this before)
'losing team' is the wordplay.
'losing' becomes 'down' ('down' can be similar in meaning to 'losing').
'team' becomes 'side' (I've seen this before).
'down'+'side'='DOWNSIDE'
'of' acts as a link.
(Other definitions for downside that I've seen before include "RC school; bad aspect" , "Somerset RC abbey/college" , "Drawback" , "Discouraging aspect" , "public school" .)