Technically you can freeze any citrus fruit, or indeed any fruit whole. You can freeze whatever you want really. But, with many foods freezing something whole can damage it. This is the case with clementines sadly, while you can actually freeze them whole, we do not recommend it as you will significantly damage the texture and taste of the fruit by doing so.
If you do want to freeze a clementine, wash, peel and separate. The best thing you can do is peel the skin off, segment the fruit, play it in a Tupperware box and freeze it like that. If you try to freeze the fruit whole, it will likely create a rather soggy result, and you will probably find that it does no longer than that deliciousness you were after.