Restrain with rope (6)
I believe the answer is:
tether
'restrain with rope' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tether that I've seen before include "Restrain within limits" , "Rope; the exasperated at the end of it" , "restricts movement" , "Restraint for animal" , "Rope restricting animal's movement" .)