Expressed at even greater length (8)

I believe the answer is:

expanded

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'expressed' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for expanded that I've seen before include "Relatively broad" , "Widened" , "Grew larger" , "Sort of polystyrene" , "Enlarged, extended" .)

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

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