Swindling or deceiving (8)
I believe the answer is:
cheating
This clue is a double definition.
'swindling' is the first definition.
(I've seen this before)
'deceiving' is the second definition.
(cheating is a kind of deceiving)
(Other definitions for cheating that I've seen before include "Swindling or defrauding" , "Acting dishonestly to gain advantage" , "Swindling or deceiving" , "Acting unfairly" , "Two-timing" .)