Element of risk, at first, in one phrase on the radio (7)

I believe the answer is:

iridium

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'element' is the definition.
(iridium is a kind of element)

I can't explain the rest of the clue.

(Other definitions for iridium that I've seen before include "Corrosion inhibitor" , "Silvery-white metal" , "Hard metal element, Ir" , "Heavy brittle metallic element of the platinum group" , "Metallic element resistant to corrosion, atomic no. 77" .)

I've seen this clue in The Independent.

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