Environmental campaigners groom ganders, according to Spooner (10)

I believe the answer is:

greenpeace

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'environmental campaigners' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

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(Other definitions for greenpeace that I've seen before include "Environmental pressure group" , "Environmental campaigners" , "Environmental activists' group" , "Environmentalists" .)

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

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