I have a pair of canvas sneakers how do I clean the canvas?

What do you need to clean off? If it's mud, then best to wait for it to dry and it will brush off. Generally hot soapy water will do the trick perfectly.

Being canvas though, it could absorb the dirt, which will make it more difficult.

All depends on what's on it! Good luck though :)

throw them in the washing machine - that's the only kind of sneakers you can do that with