to clam up
[phrase form: clam]
01
黙り込む, 突然話さなくなる
to suddenly become silent or refuse to talk, often because of nervousness, fear, or a desire to keep information secret
例
Every time the teacher asked him about his weekend, he would clam up and avoid eye contact.
先生が週末について尋ねるたびに、彼は急に黙り込んで目を合わせようとしなかった。
