Clandestine or deceptive (9)
I believe the answer is:
underhand
I believe this clue is a double definition.
'clandestine' is the first definition.
(thesaurus)
'deceptive' is the second definition.
(I've seen this before)
(Other definitions for underhand that I've seen before include "Done dishonestly" , "Surreptitious" , "Sneaky" , "Way of bowling" , "Crafty" .)