whats wrong with it? is it stained, if so.. with what? more details would be helpful.
is the canvas dirty? or is it the leather?
if its the canvas try using a shout wipe. i discovered some weird stain on my burberry canvas bag, i really wasnt sure what it was or how to clean it and i left it for months, i went and got some shout wipes (you can find small packages of them at target in the $1 section, or the travel size item section) and i just rubbed the stain away. worked perfectly.