This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 豑 is uncertain. It visually combines 豊 and 弟, but the original meaning and component function are unclear.
Since the meaning is uncertain, focus on the shape: 豊 (abundant) on the left and 弟 (younger brother) on the right. Imagine a younger brother surrounded by abundance, but the true meaning remains a mystery.
For チツ, imagine a younger brother (弟) chewing (チュウ) on a treat (ツ) from the abundant (豊) feast: chew-treat -> チツ.