Roman temple occupant he once imprisoned (8)

I believe the answer is:

pantheon

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

'roman temple' is the definition.
(ancient temple in Roman)

'occupant he once imprisoned' is the wordplay.
'PANTHEON' is hidden in amongst the letters.
However, I'm not sure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for pantheon that I've seen before include "Ancient Roman temple" , "Hall of fame" , "Roman building" , "memorial" , "list of great names" .)

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

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