Water of average density (4)
I believe the answer is:
eden
'water' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'of average density' is the wordplay.
'of' says the answer is hidden in the clue.
'EDEN' is hidden within 'average density'.
Can you help me to learn more?
(Other definitions for eden that I've seen before include "Old Testament garden" , "Former prime minister" , "Adam and Eve's first home" , "Former British PM - unspoilt paradise" , "heavenly spot" .)