Pork and apple is such a classic combination that you can pretty much guarantee that it will work well.
This pie was made with suet pastry, which is the same recipe for making a pie crust as it is for a steamed pudding. All you need is self-raising flour, suet, water and a pinch of salt. You use twice the weight of flour to suet and add just enough water to make a dough. It rolls out a lot easier than a conventional pastry too.
The filling I made was pork shoulder, cubed and braised with a mirepoix of carrots, celery and leeks, sage leaves, some stock and some medium cider. When the meat was nearly done, I added in some roughly chopped apple and left it to cool before filling the pie case and glazing it with an egg. This was then baked until the crust was golden and served with some buttered steamed cabbage and mashed potatoes.