This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
焃 combines 火 (fire) with 赤 (red). The exact historical development is uncertain, but it likely relates to the color or intensity of fire.
The left side is fire 火 and the right side is red 赤. Picture a fire burning so intensely that it glows a deep red.
For カク, imagine a red-hot fire that makes a sharp 'crack' sound as it burns: crack -> カク.