Pure
Clean
い adjective
This is a single kanji with an い on the end, meaning you know it's probably an adjective. What's the adjective form of pure? It's pure.
Since this word consists of a kanji with hiragana attached, you can bet that it will use the kun'yomi reading. You didn't learn that reading with this kanji, so here's a mnemonic to help you: "In order to stay pure and clean, you shouldn't ever do anything dirty or bad. That is the key, yo (きよ)."
でも、心の清い人にしか見えないんだって。
But apparently only those with pure hearts can see it.
「清く正しく美しく」が私のモットーです。
My motto is "Purity, Honesty, Beauty."
「水清ければ魚住まず」って言うでしょ？
You know how they say, "If the water is clear, the fish won't live there"?