This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
嚝 combines 口 (mouth) with 廣, which likely contributes the sound. The exact historical development is uncertain.
With 口 (mouth) beside 廣, imagine a wide-open mouth shouting something, but the exact meaning is unclear.
For カク, picture a mouth shouting 'kak!' like a sharp, abrupt sound: kak -> カク.