Short article probing experiment on endurance sport (9)
I believe the answer is:
triathlon
'endurance sport' is the definition.
(I know that triathlon is a type of endurance sport)
'short article probing experiment on' is the wordplay.
'short article' becomes 'th' (I can't justify this - if you can you should believe this answer much more).
'probing' means one lot of letters goes inside another (probe can mean to poke or prod into).
'experiment' becomes 'trial' (trial is a kind of experiment).
'th' put into 'trial' is 'triathl'.
'triathl'+'on'='TRIATHLON'
Can you help me to learn more?
(Other definitions for triathlon that I've seen before include "Athletics event" , "Swimming/cycling/running event" , "Contest involving swimming, running and cycling" , "Sporting contest comprising swimming, cycling and running" , "Sporting event" .)