It never fails to surprise me how cheap stewing venison is: about half the price of good stewing beef, two-thirds if you reckon with the bones. And it's hard to find meat that's more free-range than game.
A 'cobbler' is a dish of stew topped with scone-like objects, which look like cobbles. You can, of course, make a plain pie crust or eat the stew as-is with bread or potatoes.
This is a faux-medieval recipe of my own design. It's full of approximations, and very amenable to change, but remember that venison can bear a lot of spice.
Fry the onion, carrot and spices in the oil for about 10 minutes; add the wine and vinegar, bring to the boil, turn the heat down and let it boil gently for another 10 minutes or so. Let it cool to lukewarm and pour it over the meat (bone and all) in a pan small enough that the meat is completely covered. If you can't manage that, remember to turn it. Let it stand overnight in a cool place.
The next day, fish the meat out of the marinade and strain the liquid. Discard the solid bits, retain the liquid. Cut as much meat as you can manage off the bone (the lower, thinner part of the leg may be very stringy and not yield much; I recommend giving up on it before it drives you crazy). Put the bones in a pan, barely cover with cold water, throw in some peppercorns and whatever else you like in stock and put it on very low heat. It should warm up slowly to give all the flavour of the remaining meat to the stock. When it seems done, let it cool, strain it first through a sieve and then through a wet cloth to remove most of the fat, and boil it down to about half the volume.
Fry the onion and garlic, add the spices (except saffron) when it starts to colour. Add the meat and stir it around until you don't see any raw parts. Add the saffron with its water and enough of the marinade to cover the meat generously (keep the rest; you will probably need more). Bring to the boil, reduce the heat to very low, cover and stew for a few hours, stirring occasionally and adding more marinade as needed. It should never become dry. If you run out of marinade, use some of the half-done stock, or some other stock you happen to have around, or red wine and/or water. The meat will eventually become very tender, but that may take quite some time (my record is eight hours).
At this point you can leave it until tomorrow, eat it as-is, or continue making the cobbler immediately.
Make a thick roux from fat and flour and some or all of the venison stock (if you have any left over, it freezes very well). Add the stew to it, heat it through, see if it needs more thickening. Add the apple. Taste; add whatever seems to be lacking (probably salt and pepper and a small spoonful of sugar). Put the ragout in a deep oven dish large enough that the ragout will fill it halfway or a little more.
Cut the butter and salt into the flour with a pastry fork or two knives. Add the eggs, knead quickly, adding (butter)milk a little at a time until the dough hangs together and is manageable, not stiff. Roll it out on a floured board to finger thickness. Cut out circles (a port glass is the right size) and cover the surface of the dish, overlapping like scales.
Bake in a warm oven (180C/350F) until the top starts to brown and the stew bubbles up on the sides.
Root vegetables or something cabbage-like go best with it, or perhaps peas or green beans.