Build world & Build kernel question

[SUPPORT]

Hello everybody,
 
please advice me if you know.
 
I have my /usr partition 1200 MB big. I ran cvsup, then make world.
Everything was OK, but then I try build kernel and it stoped with
error - No inodes free. df show I use /usr to 103% :-)))
 
So I cd into /usr/src then make clean. df show 80% free...
Now I run make kernel again but I'm not sure, if it is not wrong way.
Can I do it such way ? Doesn't make clean "clean" my previously
installed binaries (during make world) ?????
 
Any advice is very welcome.
 
Peter Rosa