Scotch sword (4)
I believe the answer is:
foil
I believe this clue is a double definition.
'scotch' is the first definition.
(synonyms)
'sword' is the second definition.
(foil is a kind of sword)
(Other definitions for foil that I've seen before include "Frustrate - light sword" , "Parry" , "Tharwt with Sword" , "Check" , "Fencing rapier" .)