100 years to make a battery? (5)

I believe the answer is:

cages

I'm a little stuck... Click here to teach me more about this clue!

'to make a battery?' is the definition.
I can't judge whether this defines the answer.

'100 years' is the wordplay.
'100' becomes 'C' (Roman numeral).
'years' becomes 'ages' (I've seen this in another clue).
'c'+'ages'='CAGES'

Can you help me to learn more?

(Other definitions for cages that I've seen before include "Locks up" , "Enclosures made or wire or metal bars" , "prisons" , "Enclosures for animals" , "Wild animal enclosures" .)

I've seen this clue in The Independent.

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