Open the bottle of vodka and add the juniper berries, orange peel, cloves and cinnamon. (If you prefer a stronger flavour, bruise the juniper berries using a pestle and mortar first.) Put the lid back on the bottle and leave in a cool, dark place for 12-24 hrs, but no more, or the flavours may become imbalanced.
Strain the infused vodka into a jug through a fine sieve (or a coffee filter works well), then pour back into a clean bottle. Will keep for several months in a cool dark place. Mix with tonic or in a martini.