Falseness (6)
I believe the answer is:
deceit
'falseness' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for deceit that I've seen before include "Hypocrisy" , "Pretence, cheating" , "Dishonest trick" , "Duplicity or trickery" , "Dissimulation" .)