Power can, I hesitate, be a radioactive metallic element (8)

I believe the answer is:

actinium

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'a radioactive metallic element' is the definition.
(I've seen this before)

'power can i hesitate be' is the wordplay.
'power' becomes 'AC' (AC is an example).
'can' becomes 'tin' (both are metal containers).
'hesitate be' becomes 'um' (I can't explain this - if you can you should believe this answer much more).
'ac'+'tin'+'i'+'um'='ACTINIUM'

Can you help me to learn more?

(Another definition for actinium that I've seen is " Radioactive metallic element".)

I've seen this clue in the Sydney Morning Herald.

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