Fail to share (3)
I believe the answer is:
hog
'fail to share' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hog that I've seen before include "Monopolise" , "Pig; hoard selfishly" , "Domestic adult swine" , "Swine - keep for oneself" , "Selfishly keep" .)