Set it up...and stretch it out to clean it one side/panel at a time.
Pressure washers work good IF you have the right touch and nozzle and pressures..
You can't hurt cement driveways..much..:) but other items require some experience, the right nozzle & pressures and attention.

Get a BIG bucket of Dawn or other oil-grease cutting houshold sink liquid detergent and make up the bucket with hot water and soap mix.

Get out the scrub brush..Common wood one with bristles & a handle works fine.

Start at the top areas and work down.
Have the hose at hand to rinse as you clean.

Ain't fast..but it works and is safe for the canvas.

When done, let dry well and re wax or treat with a good canvas surface treatment.

Ain't nuthin' simple or easy..but anything can be done well..if one takes the time to do it..

IF it's a good tent, take the time..
Remember to dry and air well before folding-storing.Jim