I thought it might be acer negundo, the box elder, aka ash leaved maple, though the leaves appear quite long. Native to America. Used as a park tree in Europe. As a check: Louisiana Plant ID | Acer negundo (boxelder) Regards
Yes...one leaf is not enough. Acer negundo has one leaf which comprises 3 to 7 leaflets. So your pic may just show the bottom leaflet of the leaf. https://selectree.calpoly.edu/images/0000/60/original/acer-negundo-leaf-close-up.jpg http://www.ibiblio.org/openkey/intkey/images/Acer_negundo_leaf02.jpg Or it could be something totally different!
If you haven't done so, you could check that link. Young leaves are more irregular and your pic suggests a longer leaf and more symmetry. Also: Box Elder, Acer negundo L.. Do most of the leaves have 'smooth' outlines? If so, it's likely NOT box elder. Regards