We're leaving out butterflies (8)

I believe the answer is:

skippers

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'butterflies' is the definition.
Although both the answer and definition are plural nouns, I cannot see how they can define each other.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for skippers that I've seen before include "Masters" , "taking PE?" , "Sea captains" , "Captains of ships or sports teams" , "Informal ship captains" .)

I've seen this clue in The Telegraph.

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