Depressed; moo (3)
I believe the answer is:
low
This clue is a double definition.
'depressed' is the first definition.
(I know that depressed can be written as low)
'moo' is the second definition.
(I know that moo can be written as low)
(Other definitions for low that I've seen before include "Make a cow-like noise" , "Depressed or base" , "SECOND PART OF 14" , "Opposite of high" , "Not elevated, may be base" .)