PROTEUS 8.9 version Error: No model specified for CLOCK#000C. (Fast help pls.)
You must have picked a piece of equipment labeled as 'No Simulation model. Now, if you place this component in your circuit, then there will be an error named - "No model specified for ... "  

  

  

Here 'No model specified for U1:A' means that the IC named U1:A is not approved for simulation. You need to replace it with active component. 

  

So you need to replace the faulty IC with an active one. I have replaced it with the spice model. And the error is gone.   

   

In proteus, almost everything has a generic model. If there is no simulation model for your desired component, then do your simulation using another component that has the same characteristics. For designing PCB, just change the package.