An Athenian man briefly heading state, holding republican views (15)

I believe the answer is:

antimonarchical

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'state holding republican views' is the definition.
The definition suggests an adjective which matches the answer.

'an athenian man briefly heading' is the wordplay.
I cannot quite see how this works, but
'an' could be 'i' (Roman numeral for one) and 'i' is located in the answer.
'man' could be 'chic' and 'chic' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Times.

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