Attitude reversed, following a fabled writer (5)
I believe the answer is:
aesop
'fabled writer' is the definition.
(I've seen this in another clue)
'attitude reversed following a' is the wordplay.
'attitude' becomes 'pose' (attitude can mean a pose or stance).
'reversed' says the letters should be written backwards.
'following' means one lot of letters go next to another.
'pose' reversed gives 'esop'.
'esop' put after 'a' is 'AESOP'.
(Other definitions for aesop that I've seen before include "So ape the writer of fables" , "A pose of famed fable teller" , "Ancient Greek fabulist" , "he wrote in Greek" , "Poses as ancient Greek writer" .)