Good cockneys barter for geese (6)

I believe the answer is:

gaggle

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'geese' is the definition.
(gaggle is the collective noun for geese)

I don't understand the rest of the clue.

(Other definitions for gaggle that I've seen before include "Gathering of wandering geese" , "Disorderly group" , "Alternative name for a flock of geese" , "Colective noun for geese" , "Cackling sound" .)

I've seen this clue in the Sydney Morning Herald.

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