Illustrator :: Crop To Artboard (need Vector Output)

Essentially, I need to crop some work to the artboard. I've read about export option but I need this design to import into Flash.  My instructor will not permit anything but vector drawings.  I can't export to any sort of raster format or pdf.  Ideally, it needs to remain as an ai file.  When I do the import from Flash, it keeps everything outside the bounds of the artboard (highlighted in red on my screenshot).
 
This is a group project. I didn't do this drawing, I just wanted to add the perspective lines to the floor.  Now it's a bit of an untidy mess when it goes to Flash.  And Illustrator is not my strong point.  I did try unsuccessfully to "erase", Scissor, knife and a few other things but I really don't know how those tools work.  I also tried the clipping mask approach but it didn't want to combine my rectangle "mask" with the lines on the floor.
 
I'm using AI CS4 and Flash CS6.