This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
畹 combines 田 (field) with 宛, which likely contributes the sound. The exact historical development is uncertain.
The left side is a field 田, and the right side 宛 looks like a roof over a kneeling person. Picture a field with a small shelter, but its meaning is unclear.
For エン, imagine the field 田 ending at a fence: end -> エン, though the kanji's meaning is uncertain.
—