Go slow, an order upon self-defeating sports actions (3,5)
I believe the answer is:
own goals
'self-defeating sports actions' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'go slow an order' is the wordplay.
'order' indicates an anagram.
'go'+'slow'+'an'='goslowan'
'goslowan' anagrammed gives 'OWN GOALS'.
'upon' is the link.
Can you help me to learn more?
(Other definitions for own goals that I've seen before include "Actions that disadvantage the groups carrying them out" , "Personal ambitions" , "Terrible mistakes" , "Scores made against soccer team by itself" , "'Score them against your own team (3,5)'" .)