Dancing in opera outside (4-3)
I believe the answer is:
open-air
'outside' is the definition.
(open air is a kind of outside)
'dancing in opera' is the wordplay.
'dancing' indicates an anagram.
'in'+'opera'='inopera'
'inopera' anagrammed gives 'OPEN-AIR'.
(Other definitions for open-air that I've seen before include "not below roof" , "Exposed to the elements" , "Alfresco" , "Outdoor" , "Taking place outdoors" .)