Sentimental mum broke whisk (7)
I believe the answer is:
mawkish
'sentimental' is the definition.
(I know that sentimental can be written as mawkish)
'mum broke whisk' is the wordplay.
'mum' becomes 'ma' (ma can mean mother).
'broke' indicates anagramming the letters.
'whisk' anagrammed gives 'wkish'.
'ma'+'wkish'='MAWKISH'
(Other definitions for mawkish that I've seen before include "Sentimental, schmaltzy" , "Insipid; maudlin" , "Feebly sentimental" , "Soppy" , "Effusively or insincerely emotional" .)