You may try Numrich Arms. Just type it in on the net, and it will give you the website. I forget their proper web address. Gus sold by Wards were made by different manufacturers such as Winchester, Marlin, Mossberg, etc. You will need to find out who actually made that particular gun. If you can, find the Model number and name. They should be on the barrel. Put this info back on this site, and I'm sure someone will try to help you identify the actual maker. Then you can start to look for a clip to fit. Gunshows are also a source of such parts. A decent sized gun show often has vendors or collectors selling various items and parts for guns. Some of the gun magazine periodicals such as Gun Digest have things like that listed sometimes, or you could place an ad in them as looking for a particular item. Other sources are out there too.
Good luck, and I'm sure we will try to help.