Diamondbacks general manager Josh Byrnes said the team was "thrilled" to have Clark back in Arizona, where he spent three seasons and hit .266 with 53 homers and 154 RBIs.
"Just matching up day to day or late in the game is something we probably need," Byrnes said. "Obviously Tony has relationships here and hopefully can get us back in the frame of mind where we believe we can win."
Manager Bob Melvin was happy to have Clark back.
"He's able to do some things offensively, defensively, he knows how to pinch hit late in games, gives us a little production, so he's a great fit here."
The 36-year-old Clark signed with the Padres before this this season. He hit .239 (21-for-88) with one home run and 11 RBIs in 70 games.
Scribner, who turns 23 on Saturday, was 0-1 with a 1.86 ERA and one save at Class-A Visalia. The right-hander was 2-3 with a 1.57 ERA and eight saves at Class-A South Bend.
Arizona started the day in first place in the AL West, one game in front of the Los Angeles Dodgers.
San Diego manager Bud Black said Clark helped the Padres in his short stint with them.
"I thought he came to us and he was everything we had heard as far his presence on the team," Black said before Thursday night's game at St. Louis. "He was a contributor offensively for us in a basically limited role on the bench. He was there in case anything happened to [first baseman] Adrian [Gonzalez].
"Tony made a lot of contributions. He's second in the league in pinch-hits behind [Philadelphia's Greg] Dobbs. He got some clutch base hits along the way."
The Padres made no roster move Thursday and had 24 players available for the game against the Cardinals.
Scribner has 62 strikeouts in 44 innings this season and has converted all nine of his save opportunities. He will be assigned to Single-A Lake Elsinore in the California League.
Clark has spent parts of 14 major league seasons with Detroit, Boston, both New York teams, Arizona and San Diego. He is a career .264 hitter with 245 homers and 800 RBIs.
Under his contract with the Padres, Clark would have received $500,000 from the Padres if traded, but he waived that clause in order to complete the trade.
ESPN The Magazine senior writer Buster Olney and the Associated Press contributed to this report.