The Bonuses tab allows you to activate unique Clan bonuses using Religious Tractates. The number of forts defending your Capital determines the number of bonuses that you can have active at a time. All battle bonuses have a base duration of 1d 12h, while City development bonuses last for 10d 12h. You can increase this duration by researching the relevant Clan technologies.
Your City must be located on Clan territory in order to benefit from the bonus.