Defender, excited, had a negative impact (9)
I believe the answer is:
backfired
'had a negative impact' is the definition.
The answer and definition can be both related to change as well as being past participle verbs.
Perhaps you can see a link between them that I don't see?
'defender excited' is the wordplay.
'defender' becomes 'back' (left-backs and right-backs are football defenders).
'excited' becomes 'fired' (I can't explain this - if you can you should believe this answer much more).
'back'+'fired'='BACKFIRED'
Can you help me to learn more?
(Other definitions for backfired that I've seen before include "Had a bad effect on the instigator of the action" , "Went wrong" .)