I try and treat my wildlife apple tree plots or tree groupings as food plots and try and get clover established around them. (Trees have to be fenced due to the added deer draw - should be anyways until old enough to survive the browse). I also do not tend to fertilize my apple trees either unless I am starting to see some issues that could be corrected but that typically would not be corrected with N,P, or K. Im pretty certain I have never had an over abundance of nitrogen with the clover around my trees.
Most of my trees, when i keep up with them, have about a 7'x7' area around them that I have killed off the weeds to the bare dirt - mainly for rodent mice/vole control: no cover = no mice. So this may not exactly be the answer your looking for as I always strive for an area of bare dirt around my trees ,,,, They are not planted "in" clover but have clover around them and I have never had an obvious issue. Mulching them is not an option for me as I have too many trees so its round up for now and i dont want any plants near the trunks including clover.
As of last year I have bees now so weeds are not seen as the enemy like i used to think... what I did in the past was periodically (every so many years) go in and spray round-up around a large area of my trees killing back the weeds and later broadcast clover seed into the clipped back dead stubble,Im hippie'ing out and not likely to do that as much as I have an awesome dandelion bloom in the spring that the bees rock! But the spraying and seeding was a simple way to keep weeds in check, have clover and volunteer round up resistant alfalfa growing in proximity to the trees for the added deer draw - I considered the clover a plus not a negative.