Auditory equipment (4)
I believe the answer is:
ears
'auditory equipment' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ears that I've seen before include "Sear (anag.)" , "Sense organs" , "Listening organs" , "''He who has ... to hear, let him hear'' (bible)" , "Organs for 7 down" .)