Hi Glenn,
I think you could achieve this by using the Query API endpoint: https://api.clarizen.com/V2.0/services/data/Query
Example:
{
q: 'SELECT Duration FROM Timesheet WHERE WorkItem="/Task/2hqixclz7ro8ha03870ypf739318" AND ReportedDate=2019-11-18 LIMIT 1000 OFFSET 0'
}
I hope this helps.
Roland