"a permanent maintenance staff of skilled tradesmen" = staff = workers made up of "tradesmen" = people who are trained in a trade as a profession e.g., plumber, electrician, carpenter, etc.) = what kind of 'staff"? = maintenance staff = workers whose job it is to 'maintain' whatever that needs to be maintained e.g., plumbers maintain the pipes in a building, electricians maintain the electrical cords and sockets, etc. in a building, etc. = a "permanent" maintenance staff = workers who have been hired to work will always have a job at this establishment Hope this helps a little :)