Captain Clinnin was the pilot of a F4U-4B Corsair fighter with Marine Fighter Squadron 312, Marine Air Group 12, 1st Marine Air Wing. On 17 January 1952, while on a combat mission, his aircraft received a direct hit by anti-aircraft fire, went into a spin, crashed and burst into flames. He was listed as Missing in Action and was presumed dead on 16 December 1953. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Captain Clinnin was awarded the Air Medal, the Purple Heart, the Combat Action Ribbon, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.