Teller of tall tales (4)
I believe the answer is:
liar
'teller of tall tales' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for liar that I've seen before include "one trying to sell pork pies" , "Perjurer" , "Fibber" , "Tale-teller" , "Pinocchio, at times" .)