Does dad keep quiet about her? (3)
I believe the answer is:
mum
'does dad' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for mum that I've seen before include "Informal palindromic mother" , "Tight-lipped" , "Keep quiet, mother" , "old lady" , "(Keep) silent; mother" .)