Adulterated, tainted (6)
I believe the answer is:
impure
I believe this is a double definition.
'adulterated' is the first definition.
(similar in meaning)
'tainted' is the second definition.
(I've seen this in another clue)
(Other definitions for impure that I've seen before include "Tainted, not chaste" , "Lewd" , "Dirty or immoral" , "Adulterated, tainted" , "Assign a value to" .)