The Rugby Park side breezed to victory over their Perth opponents, with Boyd’s strike doing the damage alongside a Chris Kane own goal.
Clarke chose to pay attention to the striker’s temperament on an afternoon he grabbed his first goal since November.
“He’s one of a number of players who have had to be patient this season”, Clarke said. “Earlier this season we had Greg Stewart and Eamonn Brophy doing good things. In January we brought Conor McAleny and Kris has had to be patient. Sometimes when you’re a goalscorer and you’re not getting the chance to play you lose that little rhythm, so it was nice to see him get on the scoresheet.
“He’s a key part of what we do here, so it was really pleasing to see him get that goal.”
The success, Killie’s third in five matches, keeps them in with a real chance of ending their 18-year wait for European football.
Boyd led the line from the start. He thundered a header off the bar from point-blank range following a sumptuous Chris Burke cross, then he was denied by a strong left-hand from Zander Clark.
The Saints goalkeeper could do nothing soon after though, as one of his own players put the ball in his net to gift the hosts the lead.
The quality was in the delivery from Rory McKenzie as his corner was glanced towards goal by Killie captain Gary Dicker. Saints forward Kane was the unfortunate man who got the final touch to put the Ayrshire side ahead.
The second goal arrived from the right foot of Boyd. He calmly converted from the penalty spot after Jason Kerr had handled his goalbound header. The forward celebrated like a man who had not scored in months. His last goal also coming from the spot in a November defeat to Aberdeen.
Saints boss Tommy Wright said: “We didn’t start well against a good side and a side who have a lot to play for.”