Sugary syrup (7)
I believe the answer is:
treacle
'sugary syrup' is the definition.
'treacle' can be an answer for 'syrup' (treacle is a kind of syrup). I also know that 'sugary' relates to this answer.
This is all the clue.
(Other definitions for treacle that I've seen before include "flattery" , "Carroll's sisters had to live with" , "Golden syrup" , "Sweet, sticky stuff" , "Syrup-like substance" .)