To do with hearing (5)
I believe the answer is:
aural
'to do with hearing' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for aural that I've seen before include "To do with hearing or the ears" , "Received by the ears" , "Relating to the ear" , "Relating to the hearing organs" , "Relating to sense of hearing" .)