I garden in California, but have a fondness for east coast trees/shrubs. I have planted several Pawpaws and can tell you that is not one - Pawpaw leaves are obovate (wider near the tip) and your leaf is ovate. Also, that is a compound leaf, i.e., what you are holding in your hand are 3 - 7 leaflets. While the leaflets are opposite, the LEAVES are alternate. Does kind of look like something in the hickory family, but as someone else pointed out, not serrate. I'm not that into Ash, but they do have compound leaves. A good clue will be what kind of flower/fruit does it make? Much easier to identify that way. Ash produces a samara, much like a maple.
