[1] While in high school, he began pursuing the idea of an acting career, and after graduation won a role in a community theater play in San Gabriel, California.

[5][6] Clarke began his screen career with the 1958 film Dragstrip Riot, recalling that agent Byron Griffith, who had seen him perform in Glendale, arranged for an audition that eventually led to his filling the lead role.

[3] Afterward, he appeared as Tad Kimball, a friend of the character Jess Harper, played by Robert Fuller, in the episode "The Fatal Step" of the NBC Western series Laramie.

Clarke played Steve Hill in the cast of the long-running TV Western series The Virginian, remaining on the show from 1962 to 1964.

Later that decade, Clarke under his birth name wrote several scripts for the NBC espionage sitcom Get Smart,[3] which introduced the running character Hymie the Robot.

[9] In 2014, the production company L'Amoreaux/Bartlett/Race/Thomas sought actors for an independent TV pilot, Bandits and Tadpoles, written by Bartlett and Thomas and directed by Clarke, about a young boy whose daydreams put him in the American Old West of the Owen Wister novel The Virginian.

[3] In July 2003, Clarke and Drury, along with two other The Virginian co-stars, Roberta Shore and singer Randy Boone, were guests at the Western Film Fair in Charlotte, North Carolina.