Sucrose, eg (5)
I believe the answer is:
sugar
'sucrose eg' is the definition.
(I know that saccharose is a type of disaccharide)
This is all the clue.
(Other definitions for sugar that I've seen before include "Sucrose" , "Sweet white substance" , "Mild oath (granulated?)" , "Cane or beet product" , "Basic sweetener" .)