Spider mites do build webs (small tight ones that are close to the leaves, not big sprawling webs). That leaf picture looks consistent with spider mites. It also looks very dry. (Is the tree indoors?). (Spider mites also go after trees that are in a dry locale... e.g. indoors or close to a source of dry air. They also hasten the "drying out" of the leaves by taking fluids from the leaves). I've used Neem Oil successfully on getting rid of spider mites, but insecticidal soap does fine too and I found that to be very effective. But usually you lose any leaf that's as affected as that one (they dry out and fall off). Of course, it's the end of the season anyway, so maybe that doesn't matter to you. (But if indoors or you have an outlook for warmth, you could get new leaves). It's worth treating to get rid of spider mites anyway, because they'll spread to other trees. I'd recommend insecticidal soap (or even diluted dish detergent if that's what you've got on hand... spray it on in very low dilution, and then after a few hours or a half day spray with plain water. Repeat every couple of days for a week). Good luck.
Mike central NY state, zone 5a