The phrase "of one's agenda" means something that is on a person's list or plan to do. It refers to an item, task, or objective that someone has included in their schedule or to-do list and intends to complete it within a certain time frame.
Searching for new ways to reconcile the relationship between places and traffic remains at the top of the agenda for most parish councils and local communities. (politics.co.uk)
The elimination of your right to bear arms has been at or near the top of their agenda for years. (longroom.com)
I think you are slowly but surely setting somewhat of the agenda in the communication of global warming. (dotearth.blogs.nytimes.com)