How to make cornbread less crumbly?
Two things hold cornbread together:
Egg and gluten.

Gluten forms from the wheat flour interacting with the liquid. In general you don't want too much gluten or the bread will be tough and chewy instead of the characteristic tenderness of cornbread.

The egg in your recipe is similar to other recipes that call for 1 egg and 2 cups of flour. The 1/2 cup of milk is about half of the low end of what is typical.

Many recipes, especially those that add interfering ingredients like canned corn, add an extra egg for binding.  

Browsing recipes online, it is common to see more liquid than you are listing here. Even if you get another half cup of water from the canned corn it would still be the low end of liquid. More liquid in the batter will give the flour more binding ability. 
Don't overdo it. A good way to get tough cornbread is to mix it well and make a lot of gluten.

Some well rated examples:  


This recipe with creamed corn, after scaling it to two cups of flour+cornmeal, calls for both more milk and butter than yours.
This very popular recipe, while not including creamed corn, contains an extra egg and more liquid.


I would add an extra egg and increase your milk to 1 cup in your recipe.