Fox first to feature in rewritten fable (6)
I believe the answer is:
baffle
'fox' is the definition.
('baffle' can be a synonym of 'fox')
'first to feature in rewritten fable' is the wordplay.
'first to' says to take the initial letters.
'in' is an insertion indicator.
'rewritten' indicates an anagram.
The first letter of 'feature' is 'f'.
'fable' anagrammed gives 'bafle'.
'f' placed inside 'bafle' is 'BAFFLE'.
(Other definitions for baffle that I've seen before include "Puzzle and perplex" , "Sound muffler, bewilder" , "Bewilder; sound barrier" , "Damper - foil" , "Mystify, flummox" .)