This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 騞 is uncertain. It combines 馬 (horse) with 砉, but the role of 砉 is unclear.
The kanji has 馬 (horse) on the left and a complex right side. Without a clear meaning, it is hard to build a reliable mnemonic.
For カク, imagine a horse making a sharp 'kaku' sound as it gallops: kaku -> カク, though the meaning is uncertain.
—