This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
偣 combines 亻 (person) with 音 (sound). The exact historical development is uncertain, and the character is rare in modern Japanese.
A person 亻 beside sound 音 suggests something related to a person and sound, but the exact meaning is unclear. Think of a person listening intently to a sound.
For エン, imagine a person 亻 hearing a sound 音 that echoes 'en' like the start of 'end': en -> エン.