Complaining about, though it’s for your own protection (7)

I believe the answer is:

railing

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'complaining' is the definition.
(railing is a kind of complaining)

I don't understand how the rest of the clue works.

(Other definitions for railing that I've seen before include "Gin lair (anag.)" , "Complaining bitterly - barrier" , "Fulminating against the barrier?" , "Noisily protesting" , "Annoying" .)

I've seen this clue in the Evening Standard.

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