Expert; clever. Amongst the knuckling coves he is reckoned very clean; he is considered very expert as a pickpocket.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Cleaver * ClerkedNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes