A great new haunt where refreshments served outdoors
I believe the answer is:
tea garden
'where refreshments served outdoors' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'a great new haunt' is the wordplay.
'new' indicates an anagram.
'haunt' becomes 'den' (I can't explain this - if you can you should believe this answer much more).
'a'+'great'='agreat'
'agreat' is an anagram of 'teagar'.
'teagar'+'den'='TEA-GARDEN'
Can you help me to learn more?
(Other definitions for tea garden that I've seen before include "trombonist" , "Outdoor cafe" , "Public space serving scones and cream etc" , "eat alfresco here" , "Outdoor eatery" .)