Ice mass broken off 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 don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for calf that I've seen before include "Muscular back of the shank" , "Baby cow" , "A little lower" , "Young animal; part of body" , "Young of domestic cattle" .)