### Clue: Least productive 20th-century director is French (7)
### Answer: LEANEST 
 ### Explanation: Definition: Least productive
A charade of LEAN (. '20th-century director' of films such as *Brief Encounter*, *The Bridge on the River Kwai *and *Lawrence of Arabia*, but not *20th Century*, which was directed by Howard Hawks) plus EST ('is French').