The Redskins put defensive tackle Wilbur Young on the in-season injury list yesterday and probably will fill his place on the roster by signing rookie defensive end Mike Clark, who was cut last week by the Rams.

Young, deactivated for the Dallas game, has a bad shoulder that Coach Joe Gibbs said would have sidelined him the next few weeks. After four weeks, the Redskins can activate Young by using one of their three allowed moves off the injury list.

Clark, it was learned, already has tried out for the team. The former Florida star had made the Ram roster, but was released after Los Angeles found it could not cut veteran Fred Dryer, who had a no-waiver clause in his contract.

Washington played yesterday's game with only two true defensive tackles, Dave Butz and Perry Brooks, although end Karl Lorch was used at that spot briefly.

Linebacker Rich Milot aggravated a sore shoulder in the game and left the locker room with his arm in a sling. His status for Sunday's game against the New York Giants will be determined later . . . Other injuries: Art Monk (shoulder) and Lorch (jammed neck).

Theismann's 48 attempts were a personal high . . . The Cowboys have won 16 straight openers . . . All 55,045 people who bought tickets for the game attended.

Coy Bacon on the Cowboys' running success: "We were giving him (Tony Dorsett) a hole in the middle all day."