False, sham (6)
I believe the answer is:
pseudo
This clue is a double definition.
'false' is the first definition.
(I've seen this in another clue)
'sham' is the second definition.
(I know that sham can be written as pseudo)
(Other definitions for pseudo that I've seen before include "Dose up (anag.); pretentious" , "Prefix for fake" , "Fake, pretentious" , "Not genuine" , "Counterfeit" .)