org-agenda-clockreport-parameter-plist

org-agenda-clockreport-parameter-plist is a variable defined in `org-agenda.el'.
Its value is

(:link t :maxlevel 2)

Documentation:
Property list with parameters for the clocktable in clockreport mode.
This is the display mode that shows a clock table in the daily/weekly
agenda, the properties for this dynamic block can be set here.
The usual clocktable parameters are allowed here, but you cannot set
the properties :name, :tstart, :tend, :block, and :scope - these will
be overwritten to make sure the content accurately reflects the
current display in the agenda.

You can customize this variable.