Impressive display of work left in Pennsylvania and New York (7)

I believe the answer is:

panoply

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'impressive display' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

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(Other definitions for panoply that I've seen before include "Having full equipment" , "brilliant array" , "A complete or splendid array" , "Wide range" , "Apply no mix to splendid array" .)

I've seen this clue in The Times.

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