become clean; become beautiful
明日の朝パパはバルトロメオで手を洗うさぞきれいになるだろうな
Tomorrow morning, Dad will wash his hands with Bartolomeo. They’ll get really clean, I bet.
— ライフ・イズ・ビューティフル (1997)
部屋がきれいになると気持ちがいいね。
It feels good when the room is clean, doesn’t it?
いいのよいつだって泥だらけなんだから→ちっとはきれいになるでしょう。
It's fine. You're always covered in mud anyway, so you might as well get a little cleaner.
— となりのトトロ (1988)