Elderberry jam will just be equal quantities of fruit/sugar, juice of a lemon and a knob of butter and boil hard until it reaches setting point. You could cook down the elderberries and strain them first before adding the sugar etc to give you a clear jelly. Try adding some apples as well but keep the fruit/sugar ratio. If you don't get proper setting add either some apples to the mix or add pectin powder to you sugar before adding.
You could also make a jelly using the strained elderberries with some port and orange zest to serve with game or pate. I do this with redcurrants but elderberries would be good as well.