Reactor designer? (7)

I believe the answer is:

creator

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'designer?' is the definition.
(designer is a kind of creator)

'reactor' is the wordplay.
'reactor' anagrams to 'CREATOR'.
But, I am not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for creator that I've seen before include "Inventor" , "Originator - God" , "Person who makes or invents things" , "The Almighty" , "Maker" .)

I've seen this clue in the Evening Standard.

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