In Allmusic, Clark is described as "possibly the most fluent jazz French horn soloist since the great Julius Watkins in the 1950s.

He studied composition and improvisation with Jaki Byard, Ran Blake, and George Russell; and horn with James Stagliano, Thomas Newell, and Paul Ingraham.

Clark has performed or recorded with a wide variety of musicians, including in jazz: Gary Bartz, Carla Bley, Ornette Coleman, Gil Evans, John Faddis, Johnny Griffin, Dave Grusin, Jerome Harris, Jim Hall, Jimmy Heath, Anthony Jackson, Leroy Jenkins, Howard Johnson, Oliver Lake, Joe Lovano, Pat Metheny, Grachan Moncur, Gerry Mulligan, Jaco Pastorius, Rachel Z, Paquito D'Rivera, Mike Richmond, John Scofield, Frank Sinatra, Lew Soloff, Spyro Gyra, David Taylor, Toots Thielemans, the Turtle Island String Quartet, McCoy Tyner, Glen Velez, Paul Winter Consort, Akiko Yano, and the Jazz at Lincoln Center Orchestra.

Outside of jazz, he has worked with the Aspen Wind Quintet, Ashford and Simpson, the Brooklyn Philharmonic, the Fugees, Isaac Hayes, Billy Joel, B.

King, LL Cool J, Joni Mitchell, Linda Ronstadt, Diana Ross, Carly Simon, Sting, Speculum Musicae, and the Trans-Siberian Orchestra.