Kind of festival of opera in trouble
I believe the answer is:
open air
'kind of festival' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'opera in trouble' is the wordplay.
'trouble' indicates an anagram.
'opera'+'in'='operain'
'operain' anagrammed gives 'OPEN-AIR'.
'of' is the link.
Can you help me to learn more?
(Other definitions for open air that I've seen before include "definitely not in the concert hall" , "concerts?" , "like Glastonbury gigs" , "natural setting" , "Uncovered" .)