It's a little higher than the ankle - or a little lower! (4)
I believe the answer is:
calf
'little lower' is the definition.
(little cow - 'low' can mean to make a mooing sound)
I cannot understand how the remainder of the clue works.
(Other definitions for calf that I've seen before include "binding?" , "Roo's mum (A. A. Milne)" , "A little lower" , "Young bovine animal" , "Back of lower leg" .)