Dishonest person — tornado (7)
I believe the answer is:
twister
I believe this is a double definition.
'dishonest person' is the first definition.
(I've seen this before)
'tornado' is the second definition.
(I know that tornado can be written as twister)
(Other definitions for twister that I've seen before include "Colloquial name for a tornado" , "'sixties dancer?" , "One-eyed menace" , "Swindler; tornado (US)" , "Tornado (American)" .)