to shave
鬀 centers on the act of shaving, specifically cutting or removing hair from the head or body.
鬀 combines 髟 (hair) with 弟, which likely contributes the sound and may relate to the idea of cutting or ordering hair. The exact historical development is uncertain.
The top component 髟 represents long hair. The bottom component 弟 looks like a younger brother holding a razor. Picture a younger brother carefully shaving someone's long hair.
For テイ, imagine a tailor (テイ) shaving excess fabric from a garment, just as one shaves hair. The tailor's careful cutting cues テイ.