This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
挄 combines 扌 (hand) with 光 (light). The exact historical development is uncertain, but it likely relates to spreading or expanding, as suggested by its readings.
The hand 扌 beside light 光 suggests using hands to spread light outward, like opening curtains to let light fill a room.
For カク, imagine a hand spreading light in a dark room, and the light makes a sharp 'kaku' sound as it snaps on: kaku -> カク.