### Clue: Racing driver once seen with model (4)
### Answer: MOSS 
 ### Explanation: Racing driver once seen with model (4)
~~Sterling~~ Stirling MOSS is the 'racing driver once', and the 'model' is Kate. The purpose of 'seen with' is not obvious; it seems rather ~~substantisl~~ substantial to be just a linkage. But it does make for a good surface.