"Ili aĉetas oranĝojn kaj vendas sukon."
Translation:They buy oranges and sell juice.
One would assume by the context it's orange juice ;). However if you as the speaker ABSOLUTELY want to narrow it down you can always say oranĝsuko. However that's not really necessary here. You can read between the lines, just like in my sentence "However that's not really necessary here" how did you know where "Here" was?