Classic symbol of purity and grace (7)

I believe the answer is:

unicorn

(Other definitions for unicorn that I've seen before include "Fabulous beast like horned horse" , "Mythical one-horned creature" , "Mythical white animal with long horn" , "Mythical white horse with one horn" , "Mythical horned equine" .)

I've seen this clue in The New York Times.

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