Ditto on the small engine shops. The Napa out here also stocks Tygon.
Your clear tubing is likely the vinyl type. Gets very hard after exposure to fuel and heat.
Chainsaws have a "flop tube", a length of fuel line that is in the chainsaw fuel tank, with a small weight on the end, that always settles to the bottom of the tank. Allows you to hold the chainsaw in various orientations and it still gets fuel. The only thing that I know of that can be used for flop tube is that faint green Tygon. Immersed in fuel over the years, and remains flexible.
I tried various diameters of the greenish Tygon on my XS1B, and found the best fit with 3/16" (4.5mm, 0.188") ID. A tiny smear of grease, applied with a toothpick, inside the end of the fuel line, and the fuel line pushes over the pipes quite easily. The grip is enuff to forego using ring clips...