Personification of America, not one offering a symbol of peace (7)

I believe the answer is:

columba

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'peace' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for columba that I've seen before include "Iona's saint" , "Irish missionary saint" , "Iona missionary" , "Iona monastery saint" , "Saint linked to Iona" .)

I've seen this clue in The Independent.

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