Clarke was placed on the 15-day injured list Tuesday due to a left oblique strain.
With the regular season coming to an end soon and the Royals well outside of the playoff picture, Clarke will end the season on the injured list. He will finish the year with a 4.04 ERA and 1.18 WHIP over 49 innings to go along with a 3-1 record and three saves. Collin Snider was called up from Triple-A Omaha on Tuesday in a corresponding move.