Clarke has been described by Stephen Banfield as the most distinguished British female composer of the inter-war generation. However, her later output was sporadic. She suffered from dysthymia, a chronic form of depression; the lack of encouragement—sometimes outright discouragement—she received for her work also made her reluctant to compose. Clarke did not consider herself able to balance her personal life and the demands of composition: "I can't do it unless it's the first thing I think of every morning when I wake and the last thing I think of every night before I go to sleep." After her marriage, she stopped composing, despite the encouragement of her husband, although she continued working on arrangements until shortly before her death. She also stopped performing.