My take on this is that it is a good idea if you keep it not too ambitious. For example in the real world there will be plant growth under any trees grown in an orchard setting unless a stringent weed control program is in place. It might as well be clover or some other food plot type plant instead of a weed that is less helpful to the deer. It won't produce as much as in a food plot but it will pay its space as a bonus food for the deer. I would prefer clover as with minimum maintenance (annual mowing and a cleth treatment) you could get a lot of years out of it. I'm sure many guys on the forum have planted clover in their apple "orchards" and that it is working well for them. It is a proven plant for growing in partial shade. Briars might work in partial shade as well as pokeberry to name a couple. And of course in the wet spots jewel weed would be a winning secondary plant.
I have a spot I had planned to plant rye this fall under some pine trees that are trimmed high and have a south exposure; the rye won't grow all that well there maybe compared to full sun but it would be better than the grass that grows there now. And no I didn't get to it this fall. So yes as long as you don't try to grow apple trees under full canopied oaks or something similar, you are onto something constructive; there are possible winning combos that are better than what is growing on its own.
