Put the sugar and cold measurement water in a small saucepan and heat over a low heat, without stirring, until the sugar has completely dissolved. Don't be tempted to stir the mixture or the sugar will harden – tilt the pan to mix the sugar, if needed. Increase the heat and boil for 10 minutes, or until just turning pale golden.
Remove the pan from the heat and add the boiling measurement water, a tablespoon at a time, standing well back after each addition as it will spit. Tilt the pan to mix, heating gently if needed.
Put the clementines in a heatproof bowl with the star anise, then pour over the hot syrup and leave to cool for 3–4 hours. Stir the clementines and transfer to a serving dish. Serve with cream or crème fraîche.