Being shelled, company ultimately surrendered, utterly beaten (6)
I believe the answer is:
turtle
'being' is the definition.
The answer and definition can be both animals as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for turtle that I've seen before include "that flies in 2nd" , "marine animal" , "See 7" , "Kind of sea-tortoise, noted for soup" , "Cold-blooded creature" .)