Go under in a close match (4)
I believe the answer is:
lose
'go under' is the definition.
(thesaurus)
'in a close match' is the wordplay.
'in' indicates a hidden word.
'LOSE' is hidden within 'close match'.
(Other definitions for lose that I've seen before include "Don't win" , "Fail to win" , "Suffer a defeat" , "Be beaten" , "Misplace" .)