Wash the clementines, slice the clementine thinly and chop them roughly.
In a heavy bottomed pan, take the chopped clementine and add the sugar,cinnamon stick, and lemon juice and let it boil.
When boiling, turn the heat to low and let it simmer for an hour, uncover. Keep stirring once in a while.
Let it cool completely. Discard the cinnamon stick.
The marmalade will thicken when cool.
Keep in fridge and enjoy for your breakfast.