clam up
US /klæm ʌp/
UK /klæm ʌp/
1.
se taire, se refermer
to suddenly stop talking, especially when you are expected to speak
:
•
When the police started asking questions, he just clammed up.
Quand la police a commencé à poser des questions, il s'est juste tu.
•
She tends to clam up when she's nervous.
Elle a tendance à se refermer quand elle est nerveuse.