Monopolise swine (3)
I believe the answer is:
hog
I believe this clue is a double definition.
'monopolise' is the first definition.
(I've seen this in another clue)
'swine' is the second definition.
(hog is a kind of swine)
(Other definitions for hog that I've seen before include "Gourmand" , "Selfish type" , "Pig reared for slaughter" , "Pig; hoard selfishly" , "Take greedily" .)