Ice mass sheared away 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.
Can you help me to learn more?
(Other definitions for calf that I've seen before include "Young animal - part of leg" , "Young animal associated with soft leather" , "Newborn cow" , "Is it above the ankle" , "Young cow/bull" .)