Literary character, another I altered (8)
I believe the answer is:
antihero
'literary character' is the definition.
(I know that antihero is a type of literary character)
'another i altered' is the wordplay.
'altered' indicates anagramming the letters.
'another'+'i'='anotheri'
'anotheri' anagrammed gives 'ANTIHERO'.
(Other definitions for antihero that I've seen before include "Principal character without virtue" , "principal character lacking noble qualities" , "Character such as Meursault" , "central character, say" , "ignoble character" .)