Can a mouse ruin a truck clutch?

the answer is yes it could poo in the pipe and block the liquid from traveling round the pipes

The answer is more likely to be no, if a mouse chewed through a cluch hose the cluch would just fail to work, repairing the hose would repair the clutch.

It could if it isn't trained in the proper way to drive a stick-shift. The best way to teach him how to do it is to ride along side in the passenger seat and talk them through it. Be patient as it might take them a while to get used to it. Good luck with that. - Rocky_B