have a fix on;
get or have a handle on;
get or have a grasp of. Obtain (or have) a clear determination or understanding of something. For example, I was finally able to get a fix on the specifics of this problem, or No one in the press room had a handle on Balkan history, or Do you have a grasp of the situation? Similarly,
give a fix means “provide a clear understanding,” as in This briefing will give us a fix on the current situation. The usages with fix and handle are colloquialisms dating from the 1920s; those with grasp are more formal and date from the late 1600s.