Japanese bead tree
樗 refers specifically to the Japanese bead tree (Melia azedarach var. subtripinnata), a type of tree. Its meaning is a single botanical entity without broader abstract extensions.
樗 combines 木 (tree) with 雩, which likely contributes the sound チョ. The character was created to name this specific tree species.
The tree radical 木 on the left tells you it's a type of tree. The right side 雩 looks like rain 雨 falling on a curved shape, but for this rare tree, just remember: a wooden (木) tree with a distinctive right side is the Japanese bead tree.
For チョ, imagine a tiny bead from the tree dropping into your hand with a soft 'cho' sound. The bead tree makes a 'cho' when a bead falls: チョ.