Unscrupulous, dishonest (7)
I believe the answer is:
knavish
This clue is a double definition.
'unscrupulous' is the first definition.
(thesaurus)
'dishonest' is the second definition.
(I've seen this in another clue)
(Other definitions for knavish that I've seen before include "Full of dirty tricks" , "Dishonest, unscrupulous" , "like one able to beat ten?" , "Wily" , "Fraudulent" .)