Cathy Evelyn Smith, the movieland star groupie accused of killing comedian John Belushi with an injection of heroin and cocaine, has ended her battle against extradition from Canada and could return to face charges tomorrow. Belushi died March 5, 1982, at the Chateau Marmont Hotel on Sunset Boulevard from what a coroner listed as acute heroin and cocaine poisoning.

More than a year later, the 37-year-old Smith was indicted by a Los Angeles County grand jury on one count of second-degree murder and 13 counts of furnishing and administering narcotics. A Toronto judge ordered her extradited to face charges last September, but Smith appealed. It is not yet known if the Los Angeles County district attorney's office reduced the severity or number of charges to get Smith to return to the United States. South Africa 'Register'

The U.N. Center Against Apartheid has reissued what it calls a register but what others say is a blacklist of entertainers, actors and writers who perform in South Africa. Published annually since 1981 in support of a United Nations campaign for a cultural boycott to punish South Africa for its policy of apartheid, the list this year has more than 400 names.

Some of the prominent performers who have entertained in South Africa are Frank Sinatra, Helen Reddy, Elton John, Liza Minnelli, Dolly Parton, Linda Ronstadt, Susan Anton, Glen Campbell, Ray Charles, Johnny Mathis, Cher, Paul Anka, the Beach Boys, Ernest Borgnine, Telly Savalas, Goldie Hawn and Liberace.