Everything has been going right for Clement this season.
"I learned a lot getting to pitch with the guys I pitched with last year," said Clement, who played for the Cubs and with Greg Maddux last season. "It helped me mature and develop a game plan."
Manny Ramirez moved ahead of Duke Snider into 38th place on the career list with 408 homers when he connected leading off the ninth. He has seven homers in the last 11 games and 18 this season.
Chase Utley had a run-scoring double for the Phillies, who have lost eight of 11 after going 12-1 on a homestand.
"We've not only got to start hitting, we've got to start making plays and playing heads-up ball," Phillies manager Charlie Manuel said. "We're better than what we're playing now."
Clement (9-1) allowed one run and seven hits. He retired his first eight batters before reliever Geoff Geary lined a single to center for his first hit in the majors.
The right-hander, who signed a $25 million, three-year deal last December, has allowed three runs or fewer in 13 of 16 starts. He was 9-13 with a 3.68 ERA for Chicago last year.
"He's been strong, durable," Red Sox manager Terry Francona said. "His ball was moving. He's been outstanding."
Vicente Padilla (3-7) gave up five runs and eight hits -- five doubles -- in 2 2/3 innings. A former All-Star, Padilla has struggled since winning 14 games in both 2002 and 2003. He has a 6.79 ERA and hasn't pitched more than six innings in any of 11 starts this season.
Boston scored twice in the first on RBI doubles by David Ortiz and Nixon. Renteria singled with one out and scored on Ortiz's high fly off the center-field wall. Nixon lined a double to right with two outs to make it 2-0.
Varitek's two-out double in the third scored Renteria, who had singled. Ramirez, who also singled, scored when Utley made a wild throw from second to the plate. Mueller followed with a double that made it 5-0.
"We've been swing the bats good," Ortiz said. "When this team gets hot swinging the bats, it's from top to bottom."
Clement also pitched out of a jam in the fourth after Jason Michaels and Bobby Abreu hit consecutive singles to start the inning. Jim Thome grounded into a double play, and Clement struck out Pat Burrell to end the inning.
Before he fanned Burrell, Clement threw a pitch over the batter's head, but the ball hit a brick wall behind the plate and came back to Varitek, forcing Michaels to stay at third base.
Boston has scored 25 runs in Clement's last three starts after being shut out in his only loss on June 7.
"It's not so much the support, it's knowing that if you give up runs, they're going to score runs," Clement said. "It's amazing. It's fun to watch and have that offense on your side."
- Johnny Damon extended his hitting streak to 12 games with a triple in the eighth.
- Renteria's run-scoring infield single in the eighth was his 1,500th career hit.
- The Red Sox are 4-6 in Philadelphia and 12-12 against the Phillies since interleague play started in 1997.
- Burrell struck out four times and has just three hits in his last 39 at-bats.
- Geary pitched 3 1/3 scoreless innings, and hasn't allowed a run in his last 8 1/3 innings.
- The sellout crowd of 44,868 included many vocal Red Sox fans.