This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
絙 combines 糸 (thread) with 亘, which likely contributes the sound. The exact historical development is uncertain.
The left side 糸 suggests thread or cord. The right side 亘 looks like a spool or winding shape. Picture a special braided cord being wound around a spool.
For カン, imagine a can of thread: can -> カン, and the thread is wound around the spool-like right side.