clam up
phrasal verbwithclamverbuk/klæm/us/klæm/-mm-
informal(alsoshut up like a clam)tobecomesilentsuddenly, usually because you areembarrassedornervous, or do notwanttotalkabout aparticularsubject:
（通常指因为尴尬、紧张或不愿谈论某一话题而突然）沉默不语，闭口不言，拒不开口He justclamsup if youaskhim about hischildhood.要是你问起他的童年，他就干脆不说话了。
Falling silent and not speaking
- be (on) non-speakersidiom
- bite
- bitesomethingback
- biteyourtongueidiom
- button your lipidiom
- clam
- draw
- gob
- have nothing to say foryourselfidiom
- mouth
- silence is goldenidiom
- speak
- speechless
- speechlessly
- speechlessness
- stick
- stick insomeone'sthroatidiom
- tongue-tied
- unavowed
- wordless