Polish article in Die Welt reflects colourful phenomenon in the main (3,4)

I believe the answer is:

red tide

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'colourful phenomenon in the main' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'polish article in die welt reflects' is the wordplay.
'polish' becomes 'edit' (I've seen this in another clue).
'article in die welt' becomes 'der' (I've seen this in another clue).
'reflects' says the letters should be written in reverse.
'edit'+'der'='editder'
'editder' back-to-front is 'RED TIDE'.

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I've seen this clue in The Times.

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