cup
觴 centers on a drinking vessel: a cup, especially one used for serving or toasting with sake or other alcohol.
觴 combines 角 (horn, here likely referring to a horn-shaped drinking vessel) with 昜 (minus 一), which may contribute a phonetic element. The character originally denoted a cup made from horn or shaped like one.
The left side 角 suggests a horn-shaped object, and the right side looks like a container with a lid and base. Picture a horn cup filled with drink: 觴 is a cup.
For ショウ, imagine a showy toast with a horn cup: show -> ショウ, and everyone raises their 觴 in celebration.