Sound from a sty (4)
I believe the answer is:
oink
'sound from a sty' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for oink that I've seen before include "Pig's noise" , "it might be in a pen one hears" , "Beastly sound" , "Beastly noise" , "Cartoon sound of pig" .)