1970 Australian Open winner (4)
I believe the answer is:
ashe
'1970 australian open winner' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ashe that I've seen before include "US rallying champion" , "Arthur, who came to court" , "Arthur, first black Wimbledon men's singles champion, 1975" , "He was good enough to win Wimbledon" , "tennis champ" .)