Adepts are people with a particular talent for just one type of magic. They do not have an aspect detailing an Approach, but have an aspect that relates to a single magical skill.
Compared to true spellslingers, adepts don't have the full range of powers and are not treated like a supernatural character type. However, they do often have many mundane skills. Many spellslingers, and other supernaturals, tend to under estimate them since they are generally treated like mortals. However, they are often very skilled in the one type of magic they do know and that can make them dangerous. Further, they are more common than mages and in a group, they can be very dangerous. A group of adepts each skilled in a different type of magic can easily be more than a single mage can handle -- or any other supernatural type.
These characters make for interesting PCs. As NPCs they might be interesting to also play roles of either victims or antagonists. It's easy to imagine a group of these types of characters gathering together for mutual protection or to even take matters of their own defense into their own hands. Vigilante teams of adepts could be at the heart of many adventures.
Building an adept is simple. They do not have a high concept that describes an approach to magic. Instead, they simply have an aspect that describes their connection to one single magical skill. They may then pay 1 Refresh and buy that single magical skill. There are no other requirements.