Basic sugar (7)
I believe the answer is:
sucrose
'basic sugar' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sucrose that I've seen before include "Sweet substance" , "Basis of cane sugar" , "Sweetening agent -- Croesus (anag)" , "Chief component of cane or beet sugar" , "Sweetener" .)