Deck astute cheat (9)
I believe the answer is:
cardsharp
'cheat' is the definition.
(I know that cardsharp is a type of grifter)
'deck astute' is the wordplay.
'deck' becomes 'card' (I can't explain this - if you can you should give a lot more credence to this answer).
'astute' becomes 'sharp' (synonyms).
'card'+'sharp'='CARDSHARP'
Can you help me to learn more?
(Other definitions for cardsharp that I've seen before include "Cheater at, say, poker" , "Cheater at the table" , "Swindler in game" , "cheat" , "One cheating at, eg, poker" .)