We may have a terminology disconnect here.
The float valve is in the carb bowl. The clip on that helps the needle follow the float as the float sinks. Many carbs don't have that clip and just rely on gravity or fuel pressure to open the valve, so it isn't strictly necessary. But, it would bug the H out of me knowing that all the correct parts weren't in the carb.
The slide needle clip is quite another matter. The carb won't work beyond idle position if that clip is left out.
Cheers,