Different in novel setting (4)
I believe the answer is:
else
'different' is the definition.
(synonyms)
'in novel setting' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ELSE' can be found hidden inside 'novel setting'.
(Other definitions for else that I've seen before include "Besides, otherwise" , "In addition; different" , "Adverb meaning if not, otherwise" , "As an alternative" , "Other than (what is under consideration)" .)