Cutting foot off grass is wrong (3)

I believe the answer is:

sin

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'is wrong' is the definition.
(wrong can mean a sin or crime)

I cannot understand how the rest of the clue works.

(Other definitions for sin that I've seen before include "Wrongdoing" , "Wickedness" , "Behave badly" , "Fall from grace" , "Err" .)

I've seen this clue in The Times and The Sun.

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