He should be fair but doesn't play the game (7)
I believe the answer is:
referee
This clue could be a double definition.
'he should be fair but doesn't play' is the first definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'game' is the second definition.
The definition and answer can be both related to competing as well as being verbs in their base form.
Maybe you can see a link between them that I can't see?
'the' acts as a link.
Can you help me to learn more?
(Other definitions for referee that I've seen before include "One who decides" , "Football official" , "Sports official" , "Arbiter" , "Sports adjudicator" .)