In addition to what @
humfrz said it could also be a loose axle nut, they are made of soft material and can slip and deform over time, re-torque can solve the noise for a time but new nuts are cheap, the trick is that it's a 32mm so odds are you don't have that socket lying around.
Similar threads:
http://www.ft86club.com/forums/showt...92#post2414992
http://www.ft86club.com/forums/showt...50#post2389950
http://www.ft86club.com/forums/showthread.php?p=2349274
DIY's
http://www.ft86club.com/forums/showthread.php?p=1194267
http://www.ft86club.com/forums/showthread.php?t=46137
Worst case the axle is about to fail:
http://www.ft86club.com/forums/showp...3&postcount=13
Mine is clicking right now too, going to see if I can get some axle nuts for this weekend now that you've reminded me...