A low utterance from a beast (3)
I believe the answer is:
moo
'a low' is the definition.
(both can mean to make the noise of a cow)
'utterance from a beast' is the wordplay.
I cannot really see how this works, but
'from' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
The remaining letters 'mo' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for moo that I've seen before include "Cow's low" , "Irritating woman" , "Cow's call" , "Cartoon sound of a cow" , "Farmyard sound" .)