Very quick to lose the head - it's a danger (4)

I believe the answer is:

risk

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'it's a danger' is the definition.
(risk is a kind of danger)

I cannot understand how the remainder of the clue works.

(Other definitions for risk that I've seen before include "Endanger, jeopardise" , "Take a chance" , "Jeopardy" , "Possibility of bad outcome" , "Assessment of potential dangers -- any silk saris (anag)" .)

I've seen this clue in The Irish Times.

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