Homer's cry (3)
I believe the answer is:
doh
'homer's cry' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for doh that I've seen before include "Homer Simpson's exasperated cry" , "Homeric grunt of annoyance" , "an exclamation from someone who's annoyed with himself" , "First note of major scale in music" , "First note of musical scale" .)