The Client/Project/Task list on a Standard format timesheet  can be sorted alphabetically by clicking on the Client . Project . Task area (marked in the screen shot below). The list can be sorted based on Client Name, Project Name or Task Name. All the three categories can be sorted from A to Z or Z to A.

 

Note:
Some time it takes a few seconds to load the sort options and therefore it may seem like there is no option available to sort the Client/Project/Task column.