clam up
US /klæm ʌp/
UK /klæm ʌp/

1.
berdiam diri, membisu
to suddenly stop talking, especially when you are expected to speak
:
•
When the police started asking questions, he just clammed up.
Apabila polis mula bertanya soalan, dia terus berdiam diri.
•
She tends to clam up when she's nervous.
Dia cenderung untuk berdiam diri apabila dia gementar.