What often happened after 72 holes is not clearly defined (4-5)
I believe the answer is:
open-ended
'defined' is the definition.
Both the answer and definition are adjectives. Perhaps there's a link between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for open-ended that I've seen before include "Allowing free debate with no set time to finish." , "Having no fixed limit, perhaps a discussion" , "Without fixed limits or restrictions" , "Having no predetermined limit" , "With no fixed limit, not circumscribed" .)