Unpleasant noise (3)
I believe the answer is:
din
'unpleasant noise' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for din that I've seen before include "Loud noise, racket" , "A lot of noise (3)" , "'Loud, harsh noise (3)'" , "Noisy disturbance" , "Unwanted noise" .)