- just as a note, since I'm a)fond of the drink and b)make it myself,
it's to a very large extent lemon and sugar with the additional
flavouring of the elder flowers. So for all intents an purposes it's a
flavoured lemonade. :-D
You can also make a lovely cordial  from elderberry, which is a
very specific taste too. And of course you make sambuca from them;
'sambuca niger' being the latin name of the tree. It's all very
simple, and elder being so prolific, an easy thing to do yourself.
 cordial to me is a non-alcoholic syrup that is diluted to drink. I
understand this is not the case for everyone.