Restricting rope (6)
I believe the answer is:
tether
'restricting rope' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tether that I've seen before include "lead" , "Restricting rope, chain" , "Range of one's endurance: tie up (horses)" , "Restrictive rope fixed to one spot" , "Restrain a horse with a rope" .)