Did a song about wildebeests (4)

I believe the answer is:

gnus

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'wildebeests' is the definition.
('gnu' can be a synonym of 'wildebeest')

I don't understand the remainder of the clue.

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(Other definitions for gnus that I've seen before include "Large African antelopes" , "Snug (anag) -- wildebeest" , "runners in Africa" , "Gun (anag.)" , "South African antelopes" .)

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

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