Peel the clementines and, using a small knife, remove all the white pith from the peel (the pith would make it bitter). Put the peel into the large sterilised Kilner jar. Add the spices and then pour over the vodka. Seal and leave for a week, shaking the jar each day to release the flavour into the vodka.
After 1 week, dissolve the sugar in 500ml (17fl oz) of boiling water. Add this to the vodka mix, seal and then leave for another week, shaking the jar every day.
Strain into the sterilised bottles. Seal and store in a cool place. Drop some fresh spices and peel in just before giving.
Serve chilled over ice as an aperitif or use as the base for a Champagne cocktail: pour a little clemencello into a Champagne glass and top up with Champagne or Prosecco with a twist of clementine peel to decorate.