Yep, remove the little PF cover, use either your fingernail or a pocket knife. Then loosen the set screw and pull up to remove the handle. Then there's a bonnet cap under the knob, the bottom of it actually shows under the knob in the pic. Remove this bonnet nut, which will reveal the hex retainer nut that holds the cartridge valve in. Turn off the supply valve before removing or loosening the retainer nut. It may be enough to just tighten the retainer, but more likely you'll need to replace the cartridge. Remove the retainer nut and pull up on the cartridge. Take it with you to the store to get a matching one. It'll be a price fister.