Heard wound is result of saint's torture instrument (5)

I believe the answer is:

wheel

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'instrument' is the definition.
(wheel is a kind of instrument)

I can't explain the remainder of the clue.

(Other definitions for wheel that I've seen before include "Fly in a wide circle" , "Circular frame - old instrument of torture" , "Cycle; swivel" , "ring" , "Circular structure on axle" .)

I've seen this clue in The Independent.

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