To lure defender proves a disadvantage (8)
I believe the answer is:
drawback
'a disadvantage' is the definition.
(I know that drawback is a type of disadvantage)
'to lure defender' is the wordplay.
'to lure' becomes 'draw' (I've seen this in another clue).
'defender' becomes 'back' (left-backs and right-backs are football defenders).
'draw'+'back'='DRAWBACK'
'proves' acts as a link.
(Other definitions for drawback that I've seen before include "Snag" , "Limitation, disadvantage" , "Catch" , "Obstacle" , "Fly in the ointment" .)