Colours blended in Dresden (7)

I believe the answer is:

reddens

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'colours' is the definition.
(I know this)

'blended in dresden' is the wordplay.
'dresden' anagrams to 'REDDENS'.
Though, I am not sure how the anagram is indicated.

Can you help me to learn more?

(Another definition for reddens that I've seen is " Blushes".)

I've seen this clue in The Globe and Mail.

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