In general it is possible to apply multiple classes to a single widget. You just leave a space between the 2 class names. However, I don't believe that the Tabs and Accordion classes play well together so it may not be possible for the particular use case you have.
This particular forum channel is more for questions related to our training program so I have reposted it to out Product FAQ forum which will be actioned by our support team. This gets your request posted to the right channel and also they may have some additional information to add to my reply for you.