Little moo (3)
I believe the answer is:
low
This clue is a double definition.
'little' is the first definition.
(thesaurus)
'moo' is the second definition.
('low' can be a synonym of 'moo')
(Other definitions for low that I've seen before include "Deep sound of cattle - not high" , "Not high or loud" , "Moo; not high" , "Unimportant sort of owl" , "Humble; dejected" .)