Clue: Playwright leaving behind western ridge (5)
Answer: ESKER
Explanation: Definition: ridge
(w)**ESKER** [*leaving behind* W(estern)] 
*Arnold Wesker (1932-2016) was an English dramatist, whose plays included *Chicken Soup with Barley* and *Roots.
 
*An esker is a long ridge of stratified grit or sand normally formed by glaciation.