Meryl Streep is to play Joni Mitchell in a forthcoming biopic of the singer-songwriter directed by Cameron Crowe, according to record executive Clive Davis. Davis confirmed the rumours surrounding the casting at his pre-Grammys party on Saturday, reports Rolling Stone. Last year, Anya Taylor-Joy was linked to the project in the role of the younger Mitchell, as was Streep's Mamma Mia! co-star Amanda Seyfried.