A united country (4)

I believe the answer is:

peru

'country' is the definition.
(I know that Peru is a country)

'a united' is the wordplay.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'united' becomes 'U' (abbreviation).
'per'+'u'='PERU'

(Other definitions for peru that I've seen before include "Land of the Incas" , "Nazca, Cuzco here" , "Machu Picchu country" , "Homeland of Paddington Bear" , "Lima's country" .)

I've seen this clue in The Telegraph, The Times and The Independent.

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