A lawyer who takes fees from both plaintiff and defendant, or that goes snacks with both parties in gaming.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
See also the definition in Nathan Bailey's 1736 dictionary of canting and thieving slang.
Ambassador of Morocco * Amen CurlerNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes