Soreness when pulling off a river wader (5)

I believe the answer is:

egret

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'wader' is the definition.
(egret is a kind of wader)

I cannot understand how the rest of the clue works.

(Other definitions for egret that I've seen before include "Greet (anag) -- wading bird" , "Lesser white heron" , "One of a pair of waders" , "White, plumed waterbird" , "Wading bird like a heron" .)

I've seen this clue in The Times.

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