Line up at wall, every aide being reassigned (8,7)

I believe the answer is:

elevated railway

'line up' is the definition.
(railway line which is raised up)

'at wall every aide being reassigned' is the wordplay.
'being reassigned' indicates anagramming the letters (letters assigned to new positions).
'at'+'wall'+'every'+'aide'='atwalleveryaide'
'atwalleveryaide' anagrammed gives 'ELEVATED RAILWAY'.

I've seen this clue in The Times.

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