Tether (3)
'tether' is the definition.
(I know that attach is the is a more specific form of the action of tether.)
This is all the clue.
(Other definitions for tie that I've seen before include "A draw or male neckwear" , "Obligation" , "Almost level" , "hamper" , "Neck attire" .)
(Other definitions for hitch that I've seen before include "Pull up" , "Snag; tie up (animal)" , "something uplifting" , "Make fast" , "Temporary obstacle" .)
'tether' is the definition.
(I know that tether can be written as leash)
This is the entire clue.
(Other definitions for leash that I've seen before include "Rope or chain restraint" , "Spanish city famous for swordmaking" , "(Dog's) lead" , "Strip for leading, a dog say" , "Rope used to restrain an animal" .)
(Other definitions for tieup that I've seen before include "Connection with" , "Business association" .)