A model revolutionary, he was fabulously creative (5)
I believe the answer is:
aesop
'he was fabulously creative' is the definition.
(fabulous can mean relating to fables)
'a model revolutionary' is the wordplay.
'model' becomes 'pose' (synonyms).
'revolutionary' says the letters should be written in reverse.
'pose' back-to-front is 'esop'.
'a'+'esop'='AESOP'
(Other definitions for aesop that I've seen before include "Fabulous man" , "Author of many fables" , "he wrote in Greek" , "Great Greek teller of animal fables" , "Greek teller of animal tales with a moral" .)