That's part of the engine breather system. Simple description would be 'breather hose', but there is likely to another at the other end of the pipe, and maybe more, depending on how the engine breathing is set up.
As there's only one clip, it looks like Fiat glued the hose to the metal pipe, so Fiat will only supply the whole pipe with hose attached. Probably not is stock anywhere, and more expensive than necessary.
If both ends of the hose are the same internal diameter, a standard bit of engine breather hose will do the job. It does need to be specific breather hose, as it needs to be oil and fuel resistant.
Take the hose off the spigot, carefully, don't break the plastic, which may be brittle with age and heat. Measure spigot diameter and pipe diameter.
Visit a small local garage, who will probably have a coil of bulk hose, and may hopefully cut off a short length for you for pennies. Smaller car accessory shops may also be able to supply short bits. Large car parts outlets will only sell you metre lengths.
Check the other end of the pipe. You might need two bits.