Green’s Dictionary of Slang

a go-between, an intermediary, a lawyer.

1619		Middleton World at Tennis n.p.: Pity your trampler, sir, your poor solicitor [F&H].
1630		J. Taylor Works n.p.: The trampler is in hast, O cleere the way, Takes fees with both hands cause he cannot stay [F&H].
1635		R. Brome Sparagus Garden V ii: Right learned in the Law, and my sons friend Mr. Trampler, Mr. Ambodexter Trampler, you are a most notorious knave, and you shall heare on’t o’both sides, as you take fees.