Possibly great little flier (3)

I believe the answer is:

tit

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'flier' is the definition.
(type of bird)

I don't understand the remainder of the clue.

(Other definitions for tit that I've seen before include "Small garden bird" , "What you swap for tat" , "Small bird that lives off insects" , "Small songbird" , "Boob made backing" .)

I've seen this clue in the Evening Standard.

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