This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 缿 is uncertain. It combines 缶 (a jar or pot) with 后, but the original meaning and component function are unclear.
Since the meaning is unclear, focus on the shape: a jar 缶 beside 后, like a container with a ruler's seal. This may help remember the character itself.
For トウ, imagine a tall jar (缶) with a top (后) that makes a 'toe' sound when tapped: toe -> トウ.