Fable; fantasy (4)
I believe the answer is:
myth
I believe this clue is a double definition.
'fable' is the first definition.
(I've seen this before)
'fantasy' is the second definition.
(I've seen this in another clue)
(Other definitions for myth that I've seen before include "There's no truth in it" , "Wildly-held but false belief or idea" , "Unfounded belief" , "Fiction" , "A US president; a UK PM" .)