Mother keeping quiet? (3)
I believe the answer is:
mum
I believe this clue is a double definition.
'mother' is the first definition.
(informal term for mother)
'quiet?' is the second definition.
(I've seen this before)
'keeping' is the link.
(Other definitions for mum that I've seen before include "(Keep) silent; mother" , "Mother - she's the word for secrecy" , "Keep quiet, mother" , "Quiet; relative" , "Parent (who's kept or is the word!)" .)