Improvement that's needed in skyscrapers (6)

I believe the answer is:

uplift

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'improvement' is the definition.
(thesaurus)

I cannot understand how the rest of the clue works.

(Other definitions for uplift that I've seen before include "Elevate, elate" , "Elevation (of the spirit)" , "Inspire or raise" , "Increase; moral elevation" , "Boost" .)

I've seen this clue in The Globe and Mail.

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