He ruled in one Roman era (4)

I believe the answer is:

nero

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

'he ruled' is the definition.
The definition suggests a singular noun which matches the answer.

'in one roman era' is the wordplay.
'in' says the answer is hidden in the clue.
'NERO' can be found hidden inside 'one roman era'.

Can you help me to learn more?

(Other definitions for nero that I've seen before include "Cruel Roman emperor" , "Roman 9" , "Roman arsonist and fiddler" , "Roman emperor on the fiddle?" , "Ruler" .)

I've seen this clue in The Globe and Mail.

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