Answer: mum

AnswerCrossword Clue
MUMIt's "the word"?
MUM"The word," to secret keepers
MUM"...'s the word!"
MUMBritain's Queen ...
MUMNot telling
MUMOrnamental flower, for short
MUMSaying nothing
MUMClose-lipped
MUMIt may be "the word"
MUMChicago's official flower, familiarly
MUMNot divulging a thing
MUMNot talking
MUMManchester mother
MUMFall bloomer
MUMThe word, often
MUMHastings household name
MUMOrnamental flower
MUMNot exactly talkative
MUMThe word, maybe
MUMFlower, for short
mumdo not reveal what you know (about something); keep silent
MUMIt's "the word"
MUM"The word"
MUMClammed up
MUMSilent
MUMNot verbalizing
MUMBritish parent
MUM..'s the word
MUMClose-mouthed
MUMQuiet
MUMSpeechless
MUMFamily member, in Manchester
MUMUncommunicative
MUMHardly blabby
MUMTight-lipped
MUMNot blabbing
MUMThe word?
MUMFall bloom
MUMThe word, sometimes
MUMDad's mate, in Dorchester