Mention a sound location (4)
I believe the answer is:
cite
'mention' is the definition.
(to cite is to mention or quote)
'a sound location' is the wordplay.
'a sound' indicates a 'sounds like' (homophone) clue.
'location' becomes 'site' (site is a kind of location).
'site' sounds like 'CITE'.
(Other definitions for cite that I've seen before include "Quote (eg, a book)" , "Summons - quote" , "Make reference to" , "Mention as example or quote" , "Quote as evidence" .)