Clan Fame
Your clan's fame is a measure of your progress during a campaign as viewed by your rivals. It can be influenced by province ownership, battles lost or won, the personal honour of your daimyo and the legendary buildings under your control. If the level of your fame becomes too great you will be considered a threat and the Shogun (or the Emperor in the Rise of the Samurai campaign) will declare your clan enemies of the state, which will in turn lead to attacks from other clans.
Clan Fame (Fall of the Samurai)
As in Total War: Shogun 2, the capture of territory increases your clan's fame across Japan. However, now an increase in fame brings with it a new title for the daimyo, depending on his allegiance to either the Shogunate or the Emperor. When fame reaches a certain level you must choose to rally behind one power or the other, declaring war against all clans with allegiance to the opposition.
Click here to view a video tutorial about this subject.