Group aggregate dimensions in Superset dashboard

[gn02097230]

I am super new to supeset and even SQL, wonder if there is function buildt already in the software to group aggregate dimensions?
For example, my current piece chart shows $ spent by the following categories: water, cola, burger, fries.
What i want to see is a pie chart that shows $ spent by drinks and food, without changing the chart settings. Can this grouping be made on dashboard level?
What is the best practice?