Clark was averaging 7.0 points and 3.7 assists as star Marcus Smart’s understudy for the No. six Cowboys (12-1).
Clark, who was booked into the Edmund, Okla., jail, is free after posting bail.
Edmund police public information specialist Jennifer Monroe said Clark was arrested at 9:57 a.m. CT, and was the passenger in a vehicle pulled over for a seatbelt violation. Clark and the driver were both arrested for possession of marijuana.
Oklahoma State didn’t immediately issue a statement.
This is Clark’s second marijuana related issue since stepping on Oklahoma State’s campus as his earlier four-game suspension was drug related, a source told ESPN.com.
The arrest comes one day after the Cowboys lost starting center Michael Cobbins for the season with a torn Achilles.
Cobbins, a 6-8 junior, was injured in the first three minutes of Oklahoma State’s 92-66 victory over Robert Morris on Dec. 30. He has started each of the Cowboys 13 games and averaged 4.5 points , 4.3 rebounds and 1.5 blocks in 19.5 minutes of action.
"Our thoughts are with Michael, and we pray for a successful recovery," coach Travis Ford said in a statement. "We know Michael will work extremely hard and be back next season, better than ever!"
6-8 sophomore Kamari Murphy will likely move into the starting lineup when the Cowboys travel to Kansas State (10-3) on Jan. 4.