This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 夓 is uncertain. It appears to be an ancient variant or related form of 夏 (summer), but the component relationships are not clearly established.
Visually, 夓 looks like a complex version of 夏 (summer) with extra strokes. If you see it, think of an old, ornate way to write 'summer'.
For カ, imagine a summer scene where a car (カ) drives through the heat: car -> カ, and the kanji looks like an ancient summer character.