Pen for livestock (6)
I believe the answer is:
corral
'pen for livestock' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for corral that I've seen before include "Round up" , "An enclosure for horses or cattle" , "Horse enclosure out West" , "Pen for cattle in the US" , "Famous gunfight at the OK ..... in American West" .)