to pledge with wine
酧 centers on a ceremonial or social act of pledging with wine: making a toast, offering a drink, or sealing a promise with alcohol.
酧 combines 酉 (wine jar) with 守 (protect, guard), likely suggesting a guarded or formal wine offering. The exact historical development is uncertain.
A wine jar 酉 is placed beside a guard 守, as if protecting a precious drink. Picture a solemn pledge made while holding a guarded cup of wine.
For シュウ, imagine a shoe-shaped wine cup used in a pledge: shoe -> シュウ, and you drink from it to seal the promise.