Fuel line may not be best.
When you pull in the clutch leaver it applies pressure to the clutch cylinder and the cylinder is pushed outwards so the gap between the cylinder and the seal around the pushrod grows and shrinks so the cover needs to grow and shrink along with it, now the problem is there is no stop behind the pushrod seal at the motor so that seal can easily be pushed into the motor if the cover is not flexible enough.
A short piece of tube would slide back and fourth helping to keep things clean but it may not be a total solution.
I have made my own rubber seal that I have glued to the face of the original pushrod seal, it is a little larger than the original so the seals can not be pushed into the motor, this is added security and a second seal to prevent crud getting through to the original seal.
There are a few posts on this forum where others have used different materials to make a cover, have a search you may find a solution more to your liking.
Some of the 19 rides in my shed
2014 V2, Snoopy
2009 Wee, Pumbaa the pig
WR450F, The Blue Postie Bike
YZ250N smoker with rego, Stinky.
Yamaha MT09 (FZ09), The Scud missile.
Club Lead not Club Med.
He with the most toys wins.
Out of my depth in a puddle.
Live life on the edge you will see more that way.
Ridding a motorcycle keeps things in balance.
At the end of each trail and at the end of each day history is made.