Crossword Genius

Gives back to the salesman, say, when faulty (6)

Ross

I believe the answer is:

repays

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'gives back' is the definition.
('repay' can be a synonym of 'give back')

I cannot understand how the rest of the clue works.

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(Other definitions for repays that I've seen before include "Returns money loaned" , "Recompenses" , "coughs up again" , "Settles debt" , "Returns loan or favour" .)

I've seen this clue in the Evening Standard.
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