Egg pouch (3)
I believe the answer is:
sac
'egg pouch' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sac that I've seen before include "Traditional entitlement to hold court" , "Bag-like cavity" , "Bag-like part of the body" , "Bladder" , "Bodily pouch" .)