You can export any timesheet to excel by selecting "Export to Excel" menu item form the top right-hand side menu on top of timesheet view. Every Excel export contains 2 tabs. First tab contains all the worklog details used to create the timesheet. Second tab content is the same with what you are seeing on the timesheet. Although you can group multiple level on the timesheet view, for the Excel export only the first level grouping is used. For example, if timesheet view is using "project/issue type/user" 3-level grouping Excel export will only group for the first level, project.
Although most build-in issue fields are exported to Excel automatically, only custom fields selected when creating the timesheet view are exported. If you want a custom field to be exported to excel add it to your timesheet using "Extra Fields" tab of custom timesheet dialog.
Timesheet Export
Worklog Export
