tortoisegit clone option is unavailable in right-click context menu

"Hide Menus for unversioned paths" is selected, so no TortoiseGit menu is shown for paths where no git working tree could be found (you need to press shift there)

Within a working tree (in a non-ignored folder) no clone is available in the context menu. However, with newer versions (IIRC >= 2.2) also for versioned folders the Git clone entry can be shown by pressing Shift while opening the context menu.