What is this 'findmydeviced' in my location icon on the top menu bar?
"findmydeviced" is a daemon process that runs on OS X when you have enabled the "Find My Mac" option under the iCloud preference pane.

For some reason, it doesn't show up under "Security and Privacy" as an authorised system service (although this could be by design so that a non-Apple savvy thief wouldn't find it if s/he searched there).

If you no longer want to be able to track the location of your Mac via iCloud, you can uncheck the option by navigating to the iCloud preference pane. You may need to reboot in order for the daemon to unload fully.