dreadful, be frightened, fearful
悑 centers on a state of intense fear or dread: being frightened, fearful, or terrified by something dreadful.
悑 combines 忄 (heart/mind) with 甫, which likely contributes the sound. The exact historical development is uncertain, but the structure suggests a phono-semantic compound where the heart radical indicates an emotional state of fear.
The heart radical 忄 beside 甫: imagine your heart pounding with dread when you see something frightening.
For フ, picture a fearful person letting out a frightened 'foo!' sound: foo -> フ, and the heart 忄 races with fear.