Heaven on earth in walled enclosure (4)
I believe the answer is:
eden
'heaven on earth' is the definition.
(I've seen this in another clue)
'in walled enclosure' is the wordplay.
'in' says the answer is hidden in the clue.
'EDEN' can be found hidden inside 'walled enclosure'.
(Other definitions for eden that I've seen before include "Genesis garden" , "Adam and Eve's 19" , "Place of unspoiled beauty" , "Delightful place" , "The - - Project, Cornwall" .)