Didn't deny it's a selfish characteristic (6)

I believe the answer is:

agreed

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'characteristic' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?

I don't understand how the remainder of the clue works.

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(Other definitions for agreed that I've seen before include "'Concurred, assented (6)'" , "Shared an opinion" , "In harmony" , "granted" , "Said yes" .)

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

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