Crossword Genius

Checks Nadal's OK to be introduced to supporters (7)

Ross

I believe the answer is:

resists

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'checks' is the definition.
The definition and answer can be both related to competing as well as being verbs in their -s form.
Maybe they are linked in a way I don't understand?

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for resists that I've seen before include "Sisters (anag.)" , "Defends" , "Defies" , "Is hostile to" , "Struggles against" .)

I've seen this clue in The Independent.
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