He doesn't win in a close-run race (5)
I believe the answer is:
loser
'he doesn't win' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'in a close-run race' is the wordplay.
'in' says the answer is hidden in the clue.
'LOSER' can be found hidden inside 'close run race'.
Can you help me to learn more?
(Other definitions for loser that I've seen before include "Winner's opponent" , "Someone who fails consistently" , "one that's been left behind" , "Unsuccessful competitor" , "A failure, also-ran" .)