Underhand dealer's vehicle key? (4-5)
I believe the answer is:
card-sharp
'underhand dealer's' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'vehicle key?' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'key?' becomes 'dsharp' (I can't justify this - if you can you should believe this answer much more).
'car'+'dsharp'='CARD-SHARP'
Can you help me to learn more?
(Another definition for card-sharp that I've seen is " playing fiddler?".)