Pen for pigs (3)
I believe the answer is:
sty
'pen for pigs' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sty that I've seen before include "Enclosure for swine" , "Porcine pen" , "Pig pen" , "Pigs' pen" , "Pig's enclosure" .)