collar, to expose
襮 centers on the collar of a garment and, by extension, the idea of exposing or revealing what is beneath or inside.
襮 combines 衤 (clothing) with 暴, which likely contributes the sound and carries a sense of exposure or suddenness, suggesting the collar as a part of clothing that can be exposed or turned up.
The clothing radical 衤 beside 暴 (expose, violent) suggests a collar that can be turned up to expose the neck or face harsh weather.
For ハク, imagine a collar being hacked off to expose the neck: hack -> ハク, and the clothing is torn open.