This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
褖 combines 衤 (clothing) with 彖, which likely contributes the sound. The exact historical development is uncertain.
The left side 衤 suggests clothing, and the right side 彖 is a rare shape. Picture an ancient ceremonial robe with a distinctive pattern, but its exact purpose is lost to time.
For タン, imagine a tan-colored robe: tan -> タン, and the clothing radical 衤 reinforces the garment idea.