A low utterance (3)
I believe the answer is:
moo
This clue might be a double definition.
'a low' is the first definition.
(both can mean to make the noise of a cow)
'utterance' is the second definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
Can you help me to learn more?
(Other definitions for moo that I've seen before include "Cow's sound" , "unpopular woman" , "Irritating woman" , "Low (of cattle)" , "Cow's call" .)