Answer: clamup

AnswerCrossword Clue
CLAMUPStop talking
CLAMUPHush one's mouth
CLAMUPStop responding
CLAMUPGet quiet
CLAMUP"Don't say a word!"
CLAMUPRefuse to speak
CLAMUPZip one's lip
CLAMUPWithhold information
CLAMUPQuit talking
CLAMUPPlay dumb
CLAMUP"... but they always quiet themselves when I tell them to ..."
CLAMUPButton one's lip
CLAMUPSay nothing
CLAMUPGive nothing away
CLAMUPKeep mum
CLAMUPShut one's trap
CLAMUPCease talking
CLAMUPNot rat
CLAMUPSuddenly be quiet
CLAMUPRefuse to talk