Sweet syrup (7)
(Other definitions for glucose that I've seen before include "An important source of body energy" , "Naturally occurring sugar" , "Simple sugar" , "something tasting sweet" , "Type of sugar" .)
'sweet syrup' is the definition.
'treacle' can be an answer for 'syrup' (treacle is a kind of syrup). I also know that 'sweet' relates to this answer.
This is all the clue.
(Other definitions for treacle that I've seen before include "Carroll's sisters had to live with" , "Sticky produce" , "Thick syrup from sugar cane" , "Sticky fluid" , "Sweet sticky syrup" .)