Mk1 fabia vrs fuel leak to top of the tank.

Sometime ago I accidentally filled my diesel vrs with unleaded. I got off the forecourt and realised. So had to lift back seat and remove a round bung with some wires going in to the side of it. I then unscrewed the fuel tank lid and lifted out the pump. I called a friend to bring drums hoses etc and syphoned it all out. I replaced the pump into the tank and reattached the screw on lid. However after this one diesel feed or return pipe came I've put it back on but there appears to a red (I think) clip to secure the fitting. The clip on the other pipe is blue. I can't seem to find this clip anywhere. Does anybody happen to know what the part number maybe.

Thanks for reading . Can't seem to be able to add a picture :(