Units not completely honest (4)
I believe the answer is:
ones
'units' is the definition.
('one' can be a synonym of 'unit')
'not completely honest' is the wordplay.
'not completely' indicates a hidden word.
'ONES' is hidden in the letters of 'honest'.
(Other definitions for ones that I've seen before include "1 & 1 & 1" , "Aces" , "Individuals" , "Singletons" , "Units" .)