Possibly fatal contest involving many rounds? (8)
I believe the answer is:
gunfight
'involving many rounds?' is the definition.
I can't judge whether this definition defines the answer.
'possibly fatal contest' is the wordplay.
'possibly fatal' becomes 'gun' (I can't justify this - if you can you should believe this answer much more).
'contest' becomes 'fight' (I've seen this before).
'gun'+'fight'='GUNFIGHT'
Can you help me to learn more?
(Other definitions for gunfight that I've seen before include "Shoot-out (at the OK Corral?)" , "Showdown at the OK Corral" , "Battle in Westerns" , "Shooting conflict" , "At which Wyatt Earp broke the Clanton gang" .)