先約

prior engagement, prior commitment

s ẽ̞ ɰ̃ j a̠ k ɯ̟
先 priority; being first + 約 about, approximately
noun Rare #42,044
prior engagement, prior commitment An arrangement made before another invitation or plan.
JA: 今日は先約があります。
EN: I already have plans today.

私はちょっと先約が…

I already have plans…

— さらば、わが愛/覇王別姫 (1993)

トムには先約があった。

Tom already had plans.

君に気がある今夜は先約があるんだ

I have feelings for you, but I already have plans tonight.

— 恋する惑星 (1994)

Sounds similar to