Piano recital's first two pieces played alfresco (4-3)

I believe the answer is:

open-air

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'alfresco' is the definition.
(I know that alfresco can be written as open-air)

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

(Other definitions for open-air that I've seen before include "Exposed to the elements" , "Alfresco" , "Outdoor" , "outside" , "not below roof" .)

I've seen this clue in The Independent.

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