Area of the cricket field useful when it rains? (6)

I believe the answer is:

covers

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'rains?' is the definition.
Although both the answer and definition are verbs in their -s form, I cannot see how one could define the other.

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

Can you help me to learn more?

(Other definitions for covers that I've seen before include "Forms a layer over" , "Bedclothes" .)

I've seen this clue in the Evening Standard.

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