To whom two yellows can mean a red? (3)
I believe the answer is:
ref
'red?' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe 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 ref that I've seen before include "In brief, a soccer controller" , "Sports umpire" , "Whistleblower (abbr)" , "Football's whistler" , "Sports official (abbrev.)" .)