This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
貒 combines the beast radical 豸 with 耑, which may have contributed a phonetic element. The exact historical development is uncertain, and the character is rare in modern Japanese.
With no clear meaning, focus on the shape: a beast 豸 beside 耑, which looks like a sprout on a mountain. Imagine a mysterious creature that defies easy description.
For タン, imagine a tan-colored beast 豸 standing on a mountain 耑: tan -> タン, and the beast's color helps you remember the reading.