Contest held by idiot the writer has planned to avoid (12)

I believe the answer is:

preventative

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'contest held by idiot the writer' is the definition.
I can't tell whether this definition defines the answer.

'planned to avoid' is the wordplay.
'planned' becomes 'ative' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'to' says to put letters next to each other (I've seen this in other clues).
'avoid' becomes 'prevent'.
'ative' put after 'prevent' is 'PREVENTATIVE'.

'has' is the link.

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I've seen this clue in The Times.

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