Bet on team which is bottom (8)
I believe the answer is:
backside
'bottom' is the definition.
(I've seen this before)
'bet on team' is the wordplay.
'bet' becomes 'back' (I've seen this in other clues).
'on' means one lot of letters go next to another.
'team' becomes 'side' (I've seen this before).
'back'+'side'='BACKSIDE'
'which is' is the link.
(Other definitions for backside that I've seen before include "Buttocks" , "Behind" , "Seat" , "Rear" , "Bottom" .)