Born and raised in New Orleans to a politician mother and school administrator father, Clarkson earned a degree in drama from Fordham University before attending the Yale School of Drama, where she graduated with a Master of Fine Arts degree. She made her feature film debut in Brian De Palma's mob drama "The Untouchables" (1987), followed by a supporting role in Clint Eastwood's "The Dead Pool" (1988). After appearing in numerous minor roles in the early and mid-1990s, she garnered critical attention for her portrayal of a drug-addicted actress in the independent drama "High Art" (1998). Clarkson went on to appear in numerous supporting roles in such films as "The Green Mile" (1999), "The Pledge" (2001), and "Dogville" (2003).