The Diamondbacks recalled Clarke from Triple-A Reno ahead of Saturday's game against the Cubs.
Clarke has been a starting pitcher throughout his minor-league career, but he'll work out of the bullpen in what's expected to be a brief stint with the big club. After starter Merrill Kelly only lasted 3.2 innings in Friday's series opener, Clarke could be asked to provide some length in relief Saturday in order to limit the burden on Arizona's other bullpen arms.