Clarke (oblique) was activated from the 15-day injured list Thursday.
Clarke tossed an inning in a rehab assignment with Triple-A Omaha on Monday, and that was all the Royals needed to see before adding him back to the roster. Clarke has posted a 2.73 ERA, 1.01 WHIP and 31:8 K:BB over 29.2 big-league innings since the start of June, so he could be used in high-leverage spots the rest of the way.