Found this on Google:
Elderberry Cordial
Elderberries (still on stalks)
Sugar
Cloves
Pick the fruit on a dry day and stew with the stalks in a large stainless steel saucepan, with just enough water to cover.
Strain through muslin squeezing to get all the juice.
To each pint of juice add 1 lb of white granulated sugar and 10 cloves.
Boil for 10 minutes.
Allow to cool and bottle in sterile bottles with good quality plastic screw-on tops making sure you distribute the cloves evenly amongst the bottles (they act as a preservative).
The cordial can be used immediately, and will keep well for a year or two.
Taken with hot water it is renowned as a guard against colds, and a glass a day through winter is a wise precaution..
All the other recipes I came across seem to involve vodka or whisky (!)
I have just made a rather yummy Elderberry, Blackberry & Apple Jelly. The recipe's at home but I can post it later if you're interested. Don't forget the berries are toxic until cooked...had to drum that one into ds as he adores blackberries.