Come learn 2000+ kanji and 6000+ vocabulary words with WaniKani.
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means dye so the verb vocab version is to dye.
You need to dye something that you just sewed (そ) together. It's all sewed and looks like a shirt, but it's colorless. That's where the dying comes in.
I’m wondering what color to dye my hair.