Knead mother’s herb (7)
I believe the answer is:
massage
'knead' is the definition.
(synonyms)
'mother's herb' is the wordplay.
'mother's' becomes 'ma's' (ma can mean mother).
'herb' becomes 'sage' (sage is a kind of herb).
'mas'+'sage'='MASSAGE'
(Other definitions for massage that I've seen before include "See 10" , "Manipulate the muscles" , "therapeutic treatment" , "Knead" , "Rub to relieve pain" .)