They may go up the steps and under the train (5)

I believe the answer is:

rails

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'they may go up the steps' is the definition.
(handrails)

I cannot understand how the remainder of the clue works.

(Other definitions for rails that I've seen before include "Wading birds - dysfunctional person has come off them" , "Barriers of horizontal bars and supports" , "Tracks or barriers" , "secretive birds" , "Metal bars of a barrier" .)

I've seen this clue in The Times.

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