Sounded relaxed receiving acceptable answer (9)
I believe the answer is:
resonated
'sounded' is the definition.
(resonating is a kind of sounding)
'relaxed receiving acceptable answer' is the wordplay.
'relaxed' becomes 'rested' (I've seen this before).
'receiving' means one lot of letters goes inside another.
'acceptable' becomes 'on' (as opposed to not on, unacceptable).
'answer' becomes 'a' (abbreviation eg in Q and A).
'on'+'a'='ona'
'rested' going around 'ona' is 'RESONATED'.
(Other definitions for resonated that I've seen before include "Continued to ring" , "struck a chord" , "Rung" , "Vibrated sympathetically" , "Reverberated" .)