Managing permissions in large SaaS applications can be challenging, but Clerk simplifies this by providing role-based access control (RBAC) through its Organizations feature, which is crucial for B2B applications. RBAC involves assigning permissions to users based on their roles, which are often aligned with job functions, allowing users access to only what they need. In Clerk, developers can create custom roles and permissions, enhancing flexibility and security management. The example given is a team-based task management app built with Next.js, where roles like Viewer, Member, and Manager determine users' abilities to view, edit, or manage tasks. Clerk offers authorization helper functions to verify user permissions, and the sessionClaims object provides access to organizational permissions, ensuring that application functionality aligns with user roles. This approach facilitates efficient security management by adjusting application behavior based on user roles, making RBAC easily accessible for applications of any size.