Clendenin was a small shareholder in the Bank of the Western Reserve, chartered in 1811/2.
James Hazlep’s company of artillery attached to a regiment of the Ohio Militia in the War of 1812 and also as lieutenant paymaster in the Second Regiment, Ohio Militia, from August 26, 1812 – January 19, 1813.
He was assistant district paymaster in the United States Army, April 19, 1814 – December 19, 1814 at which time he was mustered out.
David Clendenin was elected in 1814 to fill the vacancy caused by the resignation of United States Representative Reasin Beall, the first man from the Western Reserve to serve in the United States Congress.
Clendenin was elected as a Democratic-Republican from Ohio's 6th congressional district to the Thirteenth United States Congress.