Depend on receiving a soft answer (5)
I believe the answer is:
reply
'answer' is the definition.
(synonyms)
'depend on receiving a soft' is the wordplay.
'depend on' becomes 'rely' (I've seen this before).
'receiving' means one lot of letters goes inside another.
'a soft' becomes 'p' (musical abbreviation for 'piano').
'rely' enclosing 'p' is 'REPLY'.
(Other definitions for reply that I've seen before include "Return" , "Retort" , "Reciprocate" , "Comeback" , "response is demanded" .)