Yes, you are able to link one issue to another.
To reference an issue within another issue, you'll use the GitHub Closing Keywords in the issue title or description.
In the example below, you can see that issues #13 and #14 start off as separate issues.
Next, on issue #13 we added the wording 'closes #14' to link the issues together.
Now, you can see that issue #13 is nested under #14
Because #13 is now connected to another issue, it will no longer appear as a standalone issue on the board.
**Note: You'll need to refresh your board after you've connected an issue for the change to take affect.