This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 赥 is uncertain. It visually combines 赤 (red) and 欠 (lack, yawn), but the original meaning and component relationship are unclear.
With no clear meaning, picture a red (赤) gap (欠) — a vivid red void that defies easy explanation, reminding you that this kanji's meaning is uncertain.
For ケキ, imagine a red gap that makes a sharp, echoing 'keki' sound when you tap it: keki -> ケキ.