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 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes