Risk you reportedly run after coming last in race (9)
I believe the answer is:
adventure
'risk' is the definition.
(adventuring is a kind of risking)
'you reportedly run after coming last in race' is the wordplay.
'you reportedly' becomes 'U' (homophone of 'you').
'run' becomes 'r' (cricket abbreviation).
'after' means one lot of letters go next to another.
'coming' becomes 'advent' (advent is the arrival or coming of something).
'last in' says to take the final letters.
The final letter of 'race' is 'e'.
'u'+'r'='ur'
'ur' after 'advent' is 'adventur'.
'adventur'+'e'='ADVENTURE'
(Other definitions for adventure that I've seen before include "Wild and exciting undertaking" , "Escapade" , "risky undertaking" , "Exciting exploit" , "The thrill" .)