The setting for Milton's lost poem? (8)
I believe the answer is:
paradise
'the setting' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I cannot understand how the remainder of the clue works.
(Other definitions for paradise that I've seen before include "Place of utter bliss" , "Felicity" , "limbo" , "Shangri-La?" , "What was lost to the poet" .)