expression, ichidan verb
take trouble; go to the trouble; put in effort for someone
Expresses that someone makes an effort or spends time doing something for another person, often implying a favor or extra care. Can also be used when the effort is for oneself, but the nuance of 'for someone' is strong.
彼は私のために手間をかけて料理を作ってくれた。
He went to the trouble of cooking a meal for me.
わざわざ手
Thank you for going out of your way to do that for me.