dilini tutmak , sesini kesmek

listen to the pronunciation of dilini tutmak , sesini kesmek
Турецкий язык - Английский Язык
(Fiili Deyim ) clam up
To become silent; to stop talking, to shut up

Maybe he … or she … was a witness who refused to clam up … a whistle blower ….

refuse to talk or stop talking; fall silent; "The children shut up when their father approached"
If someone clams up, they stop talking, often because they are shy or to avoid giving away secrets. As soon as I told her my name, she clammed up