More than a year long (5)

I believe the answer is:

yearn

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'long' is the definition.
('yearn' can be a synonym of 'long')

I don't understand the rest of the clue.

(Other definitions for yearn that I've seen before include "Have strong desire" , "Feel desire" , "wish" , "Desire strongly" , "Have an intense feeling of longing" .)

I've seen this clue in the Evening Standard.

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