Time to block low ball in sporting event (9)
I believe the answer is:
motocross
'sporting event' is the definition.
(type of motor racing event)
'time to block low ball' is the wordplay.
'time' becomes 't' (abbreviation).
'to block' is an insertion indicator (block can mean to fill a hole in something).
'low' becomes 'moo' (both can mean to make a cow noise).
'ball' becomes 'cross' (cross is a pass in football - ball can mean a pass).
't' put into 'moo' is 'moto'.
'moto'+'cross'='MOTOCROSS'
'in' is the link.
(Other definitions for motocross that I've seen before include "scrambling" , "Hairy biking" , "sport" , "Rough bike race" .)