LOS ANGELES—With three weeks to go in the regular season and the Los Angeles Dodgers locked in a tight pennant race, Clayton Kershaw is back just in time. Kershaw struck out five in his first start since July 3 and the Dodgers beat the Arizona Diamondbacks 5-1 on Monday night for their seventh straight home victory. “I missed it,” Kershaw said. “Not a lot of better feelings in the world than getting to pitch here and getting a win.” Activated from the injured list earlier in the day, Kershaw had missed 57 games with elbow inflammation. “He’s been miserable,” manager Dave Roberts said. “He hates not competing and not playing. I know he’s been waiting for this day for quite some time.” So have his teammates. “We’re all just excited to see him back out there,” third baseman Justin Turner said. The 33-year-old left-hander gave up four hits, walked one …