Original retainer that clips onto the breather element nipple sticking through the air cleaner base and holds the elbow for the hose going to the PCV valve. Ford calls this part the Crankcase Emissions Filter Retainer.
The Master Parts Catalog says this part is only for 1971 and newer cars, but this part has been found on low mile 1970 cars as well.
Ford part # D1AZ-9E628-A.