Dick Wagner, overseer -- some say perpetrator--of the ruins of Cincinnati's Big Red Machine, last week ordered John McNamara to bench Johnny Bench. And Reds' President Wagner yesterday shoved McNamara off that bench, replacing him as manager with Russ Nixon.

"He is a man's man and made every effort to do the job asked of him," Wagner said of McNamara. But, "I feel we are a better ball club than our record of 34-58 indicates . . . Russ is the man for the job."

Nixon, a 1960s catcher with Indians, Twins and Red Sox, managed Reds farm clubs 1970-75; moved up to coach for Sparky Anderson and then under McNamara, ex-A's and Padres skipper who won NL West '79 after Wagner dumped Anderson.

Wagner compromised McNamara at All-Star break by telling him whom to play, sitting down among others ex-Oriole Wayne Krenchicki--the club's hottest hitter. So Wagner (and Nixon, but not Joey Amalfitano, coach fired too) can "push forward with a youth movement to build a ball club that will play in the tradition of the Cincinnati Reds" . . .

Pittsburgh's City Council, put on warning by the Galbreath family that the Pirates might be broke and gone within three years otherwise, tentatively approved, 8-1, a new Three Rivers Stadium lease shifting maintenance costs to the city. It was that or, said Mayor Richard Caliguiri after pleas of Steelers as well, the end of Pittsburgh "as a major league sports center" . . .

Bernard Hinault continues as overall leader in bicycling's Tour de France. Peter Winnen (Netherlands) won 17th stage (of 23), 251 kilometers from L'Alpe d'Huez to Morzine, in 7:34:20; Hinault sixth and now 5 1/2 minutes ahead of overall runner-up Joop Zoetemelk (Netherlands) . . . ACC media, who properly picked North Carolina in 1981-82 basketball, favor UNC for conference football title: 61 of 74 votes. Then, defending national champ Clemson, N.C. State, Maryland, Duke, Wake Forest, Virginia . . . American U. names an assistant to Ed Tapscott, new basketball coach: Chris Knoche, 24, AU '80, ex-guard via W.T. Woodson High in Fairfax . . .

Chicago Bulls, so intent on quieting the Quintin Dailey morals mess it had the No. 1 pick skip minicamp this week: jarred anew by a Sports Illustrated piece saying a U. of San Francisco booster boosted Dailey in college with $5,000 for expenses. From USF, denials . . . One who did visit Bulls' practice: Dave Corzine, San Antonio center with N.J. Nets' fat offer sheet. Evidently up for trade, stirring rumors of Artis Gilmore to Spurs . . . Bust: Padres' Alan Wiggins allegedly tossed away a gram of something when pulled over in San Diego traffic. Recovered, maybe cocaine; felony charge. Bailed out, the fleet outfielder (29 steals in 57 games) takes voluntary leave to undergo drug treatment at team's expense.

LPGA's Jan Stephenson says her golf should be even better now that a Texas judge has pleased her by annulling one of her marriages--one she said she entered in a fit of depression "to hurt" the fellow with whom the judge ruled she has a legal, common-law marriage . . .LPGA's M.J. Smith conducts a golf clinic at Indian Spring 6 p.m. today, part of MAPGA Elizabeth Arden Classic benefiting American Cancer Society . . . Also tonight: All American Youth Bowling, at Bowl America Shirley, through Saturday . . . And the Chicken flaps at Dukes-Peninsula baseball in Alexandria.