This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 抺 is uncertain. It visually combines 扌 (hand) with 未, but the original semantic or phonetic role of 未 in this character is unclear.
With no clear meaning, focus on the shape: a hand 扌 beside 未, which looks like a tree with extra branches. Imagine a hand reaching toward an unfinished tree.
For バイ, picture a hand buying an unfinished tree: buy -> バイ, and the hand 扌 reaches for the tree-like 未.