Saw this and made a video showing you how to perform a full, leashless, clear as Evelynn. If you don't want to perform a full clear, I suggest getting a leash at Krugs and instead of going for raptors, go straight for red, then immediately go to blue.
EDIT: Youtube, what's good. Apparently the video got taken down, so I have to figure out what happened with that. In the meantime, I uploaded it to a different website.
Video: https://vid.me/27rF
Masteries: http://oi65.tinypic.com/w8x348.jpg
Runes: http://oi65.tinypic.com/28wkwig.jpg