Element of risk, at first, in one phrase on the radio (7)
I believe the answer is:
iridium
'element' is the definition.
(iridium is a kind of element)
I can't explain the rest of the clue.
Can you help me to learn more?
(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" .)