This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鵶 combines 亞 and 鳥. The exact historical development is uncertain, but it likely represents a type of bird, possibly a crow, given the 鳥 component and the reading からす.
The bird radical 鳥 on the right suggests a bird, and the left side 亞 looks like a complex nest or a dark shape. Picture a crow-like bird perched beside its tangled nest.
For ア, imagine the bird letting out a simple 'ah' sound: ア -> ア, like a crow's caw.