Could be Poe's a fabulous storyteller (5)
I believe the answer is:
aesop
'fabulous storyteller' is the definition.
(I've seen this in another clue)
'could be poe's a' is the wordplay.
'could be' indicates anagramming the letters.
'poes'+'a'='poesa'
'poesa' anagrammed gives 'AESOP'.
(Other definitions for aesop that I've seen before include "A pose by Greek writer of fables" , "his writings were fabulous" , "Fabulous man" , "very old writer" , "Greek father of fables" .)