Crossword Genius

Basis of wrestling? (3)

Ross

I believe the answer is:

mat

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'basis of wrestling?' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

This is all the clue.

Can you help me to learn more?

(Other definitions for mat that I've seen before include "Floor-pad" , "dull finish" , "Rough piece of floor-covering" , "Paint with a dull surface" , "knot" .)

I've seen this clue in the Evening Standard.
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