Nasty type first to seize article (5)

I believe the answer is:

beast

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'nasty type' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for beast that I've seen before include "Dangerous animal" , "Inhumanly cruel person" , "Monstrous person" , "Traditional poet" , "Large animal -- objectionable person" .)

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