Driving Force by Dick Francis

Jockey Freddie Croft thought he'd left the perils behind him when he retired from the jump game. These days he was happy to transport horses from their stables to the races. Until one of his drivers picked up an unlicensed passenger. And brought him back dead.

The corpse on the doorstep was Freddie's unwelcome introduction to the shadowy, big-money conspiracy which muscled into his business and started to threaten his life. But Freddie was a fighter, and winning was in his blood . . .

First identify the dangers. Then beat them out of sight . . .