In 1972, his career was derailed after he was sentenced to prison for allegedly possessing or using drugs. Due to insufficient evidence, Clémenti was released after 17 months; later he penned a book about his time in prison. After his release, he played the ever-optimistic Sailor of the Potemkin in Dusan Makavejev's Sweet Movie and the role of Pablo, the seductive saxophone player, in Fred Haines's film adaptation of Steppenwolf, Hermann Hesse's novel. Throughout his career, he continued to be active in the theatre.