* A misspelling: Perhaps you meant "waltz," a dance with a specific rhythm and pattern.
* A regional dialect word: It's possible that "walst" is used in a specific region or community, but it's not widely known.
* A made-up word: If it's not a misspelling, it might be a word invented for a specific purpose, like a fictional story or a game.
Could you please provide more context? For example, where did you see or hear this word? This will help me understand what you are looking for.