It’s not this that’s unfair (7)
I believe the answer is:
cricket
'it's not this that's unfair' is the definition.
The definition suggests a singular noun which matches the answer.
This is all the clue.
Can you help me to learn more?
(Other definitions for cricket that I've seen before include "little creature" , "short leg seen on this field?" , "Ball game" , "Jumping insect" , "Summer sport" .)