Do you have the tab parts? Sometimes you will find they are still stuck in the back of the flutter. If you do then your only option is to try and line up the parts and glue them back together. I find clear nail polish or lacquer is best as you can brush it on, it shouldnt leave brush marks and you can do one side, leave to dry and turn over and do the other side. It is not super firm but its better than risking glue which can dry a funny colour and nail polish is easily removed again if you go wrong.
If you dont have the tabs you will need to make some - you need a clear and flat plastic. What works well is the clear plastic packaging windows - you know like the plastic a G3 box would be made up off. You need to create a tab and then again attach it to the wing. The best way is to have a piece of plastic and fold it length wise 4 times - unfold it - and then fold 3 of the sides back on top of one another and glue together. Allow it to set, then glue/lacquer the one single part to the wing. Allow to set and then insert the tab into the wing. For size of the original piece of plastic it needs to be the width of the tab but 4 times the length of the tab of course.