Eccentric and intelligent cheat (4,5)
I believe the answer is:
card sharp
'cheat' is the definition.
(I've seen this before)
'eccentric and intelligent' is the wordplay.
'eccentric' becomes 'card' (card can mean an eccentric person).
'and' says to put letters next to each other.
'intelligent' becomes 'sharp' (similar in meaning).
'card'+'sharp'='CARD-SHARP'
(Other definitions for card sharp that I've seen before include "Trickster" , "wicked whist whizz?" , "You won't get a good deal out of one" , "one whose hands are not to be trusted" , "one manipulating clubs?" .)