Guilty party cancelled closer (8)
I believe the answer is:
offender
'guilty party' is the definition.
(I've seen this before)
'cancelled closer' is the wordplay.
'cancelled' becomes 'off' (similar in meaning).
'closer' becomes 'ender' (I've seen this in another clue).
'off'+'ender'='OFFENDER'
(Other definitions for offender that I've seen before include "miscreant" , "Wrongdoer" , "Transgressor, lawbreaker" , "Committer of illegal act" , "Culprit" .)