A fabulous writer takes a retrospective pose (5)
I believe the answer is:
aesop
'a fabulous writer' is the definition.
(writer of fables)
'a retrospective pose' is the wordplay.
'retrospective' says the letters should be written in reverse.
'pose' written backwards gives 'esop'.
'a'+'esop'='AESOP'
'takes' acts as a link.
(Other definitions for aesop that I've seen before include "Fabulous man" , "Poses as ancient Greek writer" , "satirical writer" , "classic author" , "Author of many fables" .)