It's obvious that a shrub might be more fitting. But even a shrub crape will eventually become a tree. If I inherited that one, I'd probably remove it, just because. But if I kept it, I'd try it tall and train it up and away in increments as it grew. Looks like the air space is fairly plentiful.
As I listed on my own site, I don't recommend fertilizing trees in most cases unless the soil is known to be nutrient deficient, especially since it increases sail)
But as the Meilleur meister said - low nitrogen if you do it. Nitro is what enlarges leaves, so it needs to be minimal. So in your case nitro should be fine - unless the ground was already fertilized.
Remember, fertilizers...all of them....organics too.. give off salts and the salts kill beneficial mycorrhize and other microorganisms. I have followed the research of Forest and Soil Biology scientists / educators in Oregon that provided that beneficial learning.
That means that IF a light fertilizing should be done at all, separate that light dose into 4 to 6 extremely light doses through the year to reduce the concentration of the leaching chemicals.
You can see my full article on Root Feeding - see menu at
http://www.mdvaden.com