Possibly great flier (3)

I believe the answer is:

auk

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'flier' is the definition.
(auk is a kind of birdanimal)

I cannot understand how the remainder of the clue works.

(Other definitions for auk that I've seen before include "Black-and-white diving bird of northern seas" , "Northern sea-bird with short narrow wings" , "Great ---, extinct seabird" , "Northern seabird with small narrow wings" , "Black/white northern diver" .)

I've seen this clue in the Evening Standard.

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