A feature of many a department store involving a real cost (9)

I believe the answer is:

escalator

I'm a little stuck... Click here to teach me more about this clue!

'a feature of many a department store' is the definition.
I can't tell whether this defines the answer.

'involving a real cost' is the wordplay.
'involving' is an anagram indicator.
'a'+'real'+'cost'='arealcost'
'arealcost' anagrammed gives 'ESCALATOR'.

Can you help me to learn more?

(Other definitions for escalator that I've seen before include "effortless steps" , "Carol eats (anag.)" , "Moving staircase" , "Moving stairway" , "financial clause" .)

I've seen this clue in The Times.

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