Pig pen (3)
I believe the answer is:
sty
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pig pen</span>' is the definition.<br/ ><span class="explanation-format__explanation">(where pigs are kept)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for sty that I've seen before include "Farmyard enclosure" , "Pig-house" , "Pigpen; swelling" , "Sore on eyelid" , "Enclosure for swine" .)