Sports event in pool where this person's invested half of capital (8)
I believe the answer is:
biathlon
'sports event in pool where this person's invested half of capital' is the definition.
The definition suggests a singular noun which matches the answer.
This is all the clue.
Can you help me to learn more?
(Other definitions for biathlon that I've seen before include "Contest in two events, like cycling and running" , "Shooting contest by skiers with rifles" , "winter sports event" , "Sport combining rifle shooting and cross-country skiing" , "Contest in two sporting disciplines, say cycling and running" .)