Clue: Liberate one French composer (6)
Answer: UNCAGE
Explanation: Liberate one French composer (6)
**UN** ("one" in "French") + (John) **CAGE** (American "composer" whose most famous work is '4'33' in which the orchestra does not play any instruments, but the "music" is whatever sounds there are in the environment in which the "performance" is taking place)