Born on a plantation in Prince Georges County, Maryland, Clarke attended grammar and high schools. He studied law. He was admitted to the bar and practiced in Niagara County, New York. Surrogate of Niagara County in 1808 and 1809. He served as member of the State assembly 1809-1811. He served in the State senate 1813-1816. County clerk in 1815 and 1816.