Rosemary, for one, was collared by Father Brown (4)

I believe the answer is:

herb

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

'rosemary' is the definition.
(thesaurus)

'one was collared by father brown' is the wordplay.
'HERB' is hidden within the letters.
However, I am not sure how this is indicated.

'for' acts as a link.

Can you help me to learn more?

(Other definitions for herb that I've seen before include "bay perhaps" , "'Sage or rosemary, say (4)'" , "Basil, for example, is one" , "Basil, perhaps" , "Eg, sage" .)

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

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