One absent after duel goes wrong (9)
I believe the answer is:
defaulter
'one absent' is the definition.
'after duel goes wrong' is the wordplay.
'goes wrong' indicates an anagram.
'after'+'duel'='afterduel'
'afterduel' anagrammed gives 'DEFAULTER'.
(Other definitions for defaulter that I've seen before include "Guilty soldier" , "Person avoiding court action" , "He hasn't paid his bills" , "He fails to show up" .)