Sonorous (8)
I believe the answer is:
resonant
'sonorous' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for resonant that I've seen before include "Tending to prolong sound, echoing" , "Booming" , "Evoking memories" , "Continuing to sound clearly and deeply" , "Deep, clear and continuing to sound or reverberate" .)