Race injury (6)
I believe the answer is:
strain
I believe this is a double definition.
'race' is the first definition.
(I've seen this before)
'injury' is the second definition.
(I know that strain is a type of injury)
(Other definitions for strain that I've seen before include "Put through a perforated device to separate" , "Tension and exertion" , "Great effort - sieve" , "Strive; ancestry" , "Injure (a muscle); distinct breed" .)