This is three months old but what the heck. I love the topic.
Two things come to mind:
-Brush pile, even a small one (tucked behind a shrub?) provides cover for ground nesting birds or critters your owls might want for breakfast.
-This is something I'm struggling with: how to balance clean up with plant and bee survival. We're in the country, so circumstances are different, but what I think I'm going to do is leave the leaf debris around the plants that attracted the most pollinators, especially late ones (asters, sedums, dahlia zone (though I still have to dig up the tubers). I put a bunch of hollow stuff in little patches, for nesting, and I know some bees dig under leaf litter while others bury in bare soil....so I'm doing my best to try to let their habits guide some of what I do and don't to prepare for the off-season.
And if a plant has seeds or hollow stems or winter interest I leave it up for birds, hibernating bees, and my bored January eyes.
Also, this might matter even though your yard is smaller: in the spring my focus goes to the warmest part of the yard first, and I don't rush to clean up areas where I know the soil is too cold for either plant growth or bees waking up. I just let it sit around until it's really in a position to perk up.
