You can create a hyperlink variable within a variable. For example you can create an "event" variable, insert this into your template, and then have a custom "event url" you want linked to the first variable. You can create the customized variable option through the following steps:

Step 1: Create the custom variable(s) you'd like to use. (learn more about custom variables in this article)

Step 2:  Click on your "Campaigns" and Go to "Templates":

Step 4: Choose a template and enter the first variable into your template (for this example, we'll use "event"):

Step 5: Highlight the variable and choose the hyperlink button:

Step 6: Enter in the second variable into the hyperlink URL box (for this example, we'll use "event_url") and click "ok" once finished: