This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 頥 is uncertain. It appears to be a variant or related form of 頤, which combines 頁 (head) with a phonetic component, but the specific origin of the 臣-containing left side is unclear.
Since the meaning is unclear, focus on the shape: a head-related 頁 on the right, and a minister-like 臣 on the left. Imagine a minister bowing his head deeply, but remember the meaning is uncertain.
For イ, imagine an eagle (イーグル) perched on the head (頁) of the minister (臣): eagle -> イ, but the meaning remains uncertain.