Means for controlling weather, say? (4)

I believe the answer is:

rain

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'weather say?' is the definition.
'rain' can be an answer for 'weather' (I've seen this before). I am unsure of the 'say?' bit.

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

Can you help me to learn more?

(Other definitions for rain that I've seen before include "Storm" , "The ---, it ---eth every day (T.Night)" , "Fall wetly" , "See 12" , "Weather - shower" .)

I've seen this clue in The Guardian.

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