Crossword Genius

Thwart, using this sword? (4)

Ross

I believe the answer is:

foil

I believe this is a double definition.

'thwart' is the first definition.
(I've seen this before)

'this sword?' is the second definition.
(foil is a kind of sword)

'using' acts as a link.

(Other definitions for foil that I've seen before include "metal used in > sword" , "Thwart - contrasting thing - sword" , "Thin metal - sword" , "Piece of thin and flexible sheet metal" , "Hinder - prevent" .)

I've seen this clue in The Times.
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