Clarkson later was a three-year starter for coach Jack Elway at San José State University, where he holds several passing records and was named to the Academic All-American teams in 1981 and 1982 [REF].
After going undrafted in the 1983 NFL Draft, Clarkson played a season for the Denver Broncos and two seasons for the Canadian Football League's Saskatchewan Roughriders in 1983 and 1984 [REF].