gather
欑 centers on bringing things together into one place: gathering or assembling. The single given meaning is straightforward, with no major distinct senses to reconcile.
欑 combines 木 (tree/wood) with 贊, which likely contributes the sound and may relate to assembling or gathering. The exact historical development is uncertain.
Picture a tree (木) with many branches gathering together around the trunk, like the right side 贊 suggests a cluster of items being assembled.
For サン, imagine gathering under the sun (サン) near a big tree: sun -> サン, and everyone gathers there.