D2 td5 fuel tank breather hose

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The hose has split on top of the tank at the hose clamp, my question is,

1. Is it a special hose, it looks thicker at the hose clamp?
2. The hose clamp has a cap or something over the top so I can't undo it, is there a trick to undo it?
3. Can I use a piece of transmition hose or dose it have to be fuel line hose?

Thanks for your help
Jason.