Zest and juice the clementine, then remove the seeds from the pomegranates.
Combine all the ingredients in a pan, except the pomegranate seeds and gin.
Heat gently until the sugar has dissolved. Bring to a gentle boil then take off the heat and leave to cool.
Add the pomegranate seeds and gin and decant into a large glass container or several glass bottles. Leave to macerate for 2 weeks, or as long as possible.
Strain and pour into your chosen bottles (leave unstrained if you think it looks more interesting). It will keep in a cool, dark place for a few months.