A thorough-paced rogue, a sly designing fellow: in opposition to a shallow or foolish one.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
death’s head upon a mop-stick * deft fellowNathan Bailey's 1721 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes