Sound staff of life brought up (4)
I believe the answer is:
bred
'brought up' is the definition.
(to breed is to bring up or raise)
'sound staff of life' is the wordplay.
'sound' shows a homophone (sound like).
'staff of life' becomes 'bread' (synonyms).
'bread' is a homophone of 'BRED'.
(Other definitions for bred that I've seen before include "Reared" , "(Well) brought up" , "Brought up (to behave in particular way)" , "Procreated" , "Developed (animal variety)" .)