Idyllic place (4)
'idyllic place' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for xanadu that I've seen before include "Kublai Khan's capital" , "Where Kubla Khan decreed his pleasure-dome be built" , "Winter palace of the Kubla Khan, according to Coleridge" , "'In . . . . . . did Kubla Khan / a stately pleasure-dome decree' (Coleridge)" , "Idealised place of great luxury" .)
'idyllic place' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eden that I've seen before include "In need of a great garden" , "PM, 1955-57" , "Adam and Eve's 19" , "Paradise - ex-PM" , "project in the south west" .)