Fabricator; false witness (4)
I believe the answer is:
liar
I believe this is a double definition.
'fabricator' is the first definition.
(I've seen this before)
'false witness' is the second definition.
(I've seen this in another clue)
(Other definitions for liar that I've seen before include "one telling a story" , "Person regularly 'economical with the truth'" , "Phoney" , "one trying to sell pork pies" , "One whose pants are on fire?" .)