cotton clothes of a boy servant
裋 refers specifically to the cotton clothes worn by a boy servant, a narrow historical garment term.
裋 combines the clothing radical 衤 with 豆, which likely provides the sound. The character is a specific historical term for servant's cotton clothing.
The clothing radical 衤 beside 豆 (bean) suggests simple, humble cotton clothes, like those a boy servant might wear while handling beans.
For シュ, imagine a boy servant in cotton clothes shooing away flies: shoo -> シュ, and the simple garment fits the scene.