1950s British PM (4)
I believe the answer is:
'1950s british pm' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eden that I've seen before include "Old Testament garden" , "Place of unspoiled beauty" , "Someone once seen in Number Ten's" , "Idyllic garden" , "PM, 1955-57" .)