A low cry (3)
I believe the answer is:
moo
I believe this is a double definition.
'a low' is the first definition.
(both can mean to make the noise of a cow)
'cry' is the second definition.
(I know that moo is a type of cry)
(Other definitions for moo that I've seen before include "Bovine low" , "Cartoon sound of a cow" , "Cow's low" , "Cow's sound" , "Guernsey noise?" .)