Safety Clarence Vaughn's left shoulder appears to be worse than originally thought and the Washington Redskins say he may not play this week against the Los Angeles Rams and is questionable for the Sept. 9 regular season opener.

If he's out, that would probably open up a spot for fourth-round draft pick Ricco Labbe, a Washington native who played at Archbishop Carroll High School and Boston College.

Redskins coaches have been impressed with Labbe, but he appeared to be caught in a numbers crunch. The Redskins keep only four safeties, and veterans Alvin Walton, Todd Bowles, Brad Edwards and Vaughn were ahead of him.

Vaughn was hurt last week and X-rays were negative. However, the shoulder still is sore. Quarterback Quandary

The maneuvers for rookie quarterback Cary Conklin may be interesting. Team officials said his right knee still is bothering him, but Conklin said, "As far as I'm concerned, it's 100 percent."

The Redskins traditionally have had a tough time keeping young quarterbacks healthy, especially when it was clear they weren't going to make the team. Mark Rypien spent two seasons on injured reserve with injuries that were far from life-threatening and Stan Humphries was sidelined a season by an odd blood disorder.

The Redskins will keep only three quarterbacks and Rypien, Humphries and Jeff Rutledge appear to have won the jobs. Coach Joe Gibbs said it was unlikely Conklin would play in Friday's preseason game against the Rams at RFK Stadium. Uncertain End

It's also unlikely that defensive end Fred Stokes will play. General Manager Charley Casserly said there is still a chance Stokes will be ready for the Phoenix Cardinals on Sept. 9, but until he tests his tender shoulder in practice, there will be no way to know.

Stokes has practiced only twice since the first part of training camp and hasn't played in a preseason game. The shoulder twice has popped out of place (or given him that sensation) and he's doing weight work to get the area stronger. . . .

Offensive lineman Ray Brown, who suffered a sprained knee Saturday night in Cleveland, returned to practice. Casserly said he still has soreness in the knee. . . . With yesterday's roster moves, the Redskins have only seven rookies left on their squad. None is a free agent, and at the moment, there will be no diamonds-in-the-rough story. . . .

The Redskins offensive line has not allowed a sack through three preseason games. . . . The Redskins have 85 points. Only in 1988 and 1972 did they score more points their first three preseason games. . . . Chip Lohmiller is 10 for 10 on extra points and five for five on field goals. His average field goal has been 31.6 yards. . . . Gerald Riggs's 72-yard run against the Browns was the longest of his career.