Finish third in race and be defeated (5)
I believe the answer is:
close
'finish' is the definition.
(closing is a kind of finishing)
'third in race and be defeated' is the wordplay.
'third in race' becomes 'c' (I am not sure about this - if you are sure you should believe this answer much more).
'and' is a charade indicator (letters next to each other).
'be defeated' becomes 'lose' (I've seen this before).
'c'+'lose'='CLOSE'
Can you help me to learn more?
(Other definitions for close that I've seen before include "On intimate terms" , "on very affectionate terms" , "Cathedral's precincts" , "Approaching - tight - finish" , "Dense; nearby" .)