He stands for fair play (6)
I believe the answer is:
umpire
This might be a double definition.
'he stands' is the first definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'fair play' is the second definition.
Both the definition and answer are singular nouns.
Maybe they are linked in a way I don't understand?
'for' acts as a link.
Can you help me to learn more?
(Other definitions for umpire that I've seen before include "Game judge" , "Official at a cricket match" , "Football official" , "Impartial supervisor" , "The ref in cricket match" .)