Roundup accessory (6)
I believe the answer is:
lariat
'roundup accessory' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lariat that I've seen before include "Long noosed rope for catching animals" , "A cowboy's rope for catching cattle" , "Rope used as a lasso" , "Cattle-catching rope" , "Rope with running loop at one end" .)