This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
虶 combines 虫 (insect) with 于, but the exact historical development and original meaning are uncertain.
Since the meaning is unclear, focus on the shape: an insect 虫 beside 于. Picture a strange bug with a hook-like tail (亅) and two lines (二) on its back.
For ウ, imagine the insect making a soft 'oo' sound as it crawls: oo -> ウ.