Mum and daughter subdued (5)
I believe the answer is:
muted
'subdued' is the definition.
(both can mean restrained or subtle)
'mum and daughter' is the wordplay.
'mum' becomes 'mute' (to keep mum is to remain silent).
'and' says to put letters next to each other.
'daughter' becomes 'd' (genealogical abbreviation).
'mute'+'d'='MUTED'
(Other definitions for muted that I've seen before include "Piano" , "Temporarily speechless" , "Hushed or stifled" , "Muffled, subdued" , "Viola is sometimes" .)