Robert Duvall leads a superb cast of American character actors in 1983’s Tender Mercies (8 p.m., WFLX-Ch. 29), a drama about the redemption of an alcoholic musician. The screenplay, by Horton Foote (To Kill a Mockingbird), unfolds with the confident style of a writer at the peak of his game. Duvall plays a country singer attempting a comeback, who is invigorated by his relationship with a young widow (Tess Harper) and her son. The supporting cast includes Wilford Brimley, Betty Buckley, Ellen Barkin and Allan Hubbard. Duvall and Foote won Academy Awards.