The Grammy Award–winning bandleader for The Roots spoke with Fresh Air's Terry Gross about his film on the funk musician who led Sly & the Family Stone in the 1960s and '70s.

Iranian-Danish director Ali Abbasi’s “The Apprentice,” the tale of how a young Donald Trump fell into the orbit and under the spell of the venal lawyer Roy Cohn in the 1970s, struggled to get ...