Defender has boot out for rebound (8)
I believe the answer is:
backfire
'rebound' is the definition.
(thesaurus)
'defender has boot out' is the wordplay.
'defender' becomes 'back' (I've seen this before).
'has' means one lot of letters go next to another.
'boot out' becomes 'fire' (boot out can mean to fire or dismiss).
'back'+'fire'='BACKFIRE'
'for' acts as a link.
(Other definitions for backfire that I've seen before include "Rebound adversely (on the originator)" , "Have the opposite and damaging effect to that intended" , "Come home to roost" , "Cause a result opposite to that intended" , "explosion" .)