Q: clean install yosemite, couldn´t install aperture afterwards

Hi, 2teddy3.  

Thank you for visiting Apple Support Communities.  

I would need more information regarding any errors received and clarification on exactly what is happening to provide a better answer.  However, here is a troubleshooting article that may help.  .  

Troubleshooting the Mac App Store

http://support.apple.com/kb/TS3624

Cheers, 

Jason H