This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
絗 combines 糸 (thread) with 回 (turn, revolve), suggesting thread winding or revolving. The exact historical development is uncertain.
Thread 糸 winding around a revolving shape 回: picture a spool of thread turning round and round.
For コツ, imagine a spool of thread making a sharp 'kotsu' sound as it clicks into place while revolving: kotsu -> コツ.