Probe deep inlet (5)
I believe the answer is:
sound
I believe this is a triple definition!
'probe' is the first definition.
(thesaurus)
'deep' is the second definition.
(synonyms)
'inlet' is the third definition.
(I've seen this in another clue)
(Other definitions for sound that I've seen before include "Unimpaired" , "Valid" , "Noise; in good condition" , "Not diseased or damaged - listen" , "note, for instance" .)