Pig enclosure (3)
I believe the answer is:
sty
'pig enclosure' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sty that I've seen before include "Pig-pen and eye infection" , "Hog house" , "Pigs' pen" , "Pigpen; swelling" , "Enclosure for swine" .)