Trace race (4)
I believe the answer is:
dash
'race' is the definition.
(dashing is a kind of racing)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for dash that I've seen before include "display of instruments" , "Punctuation mark; hurry" , "If you're smart, you'll cut one" , "- - ; panache" , "Stylish vigour; frustrate (hopes)" .)