Sweet melon (8)
I believe the answer is:
honeydew
'sweet melon' is the definition.
(honeydew is a kind of sweet melon)
This is the entire clue.
(Other definitions for honeydew that I've seen before include "Sweet substance produced by aphids" , "Food supplied and eaten by 20s (and Kubla Khan?)" , "Melon variety" , "Melon - Owen Hyde (anag)" , "Type of melon" .)