Radiant: "WARNING - The preferred point for defining clocks is top level ports and driver pins. Pad delays will not be taken into consideration if clocks are defined on nets."
In Radiant, this warning occurs because the user have some create_clock constraints defined on nets. If the clocks have connected top-level ports or driver pins, the user must consider moving the constraint objects of the create_clock constraints to these instead of nets.
To remove this warning, user needs to define the clocks using top-level ports and driver pins to allow timing analysis to check complete timing information on the clocks.