In which a love match couldn't be more one-sided! (6)
I believe the answer is:
tennis
'in which a love match couldn't be more one-sided' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
This is all the clue.
Can you help me to learn more?
(Other definitions for tennis that I've seen before include "Roger Federer's game - anyone for it?" , "Racket sport" , "Table -, - elbow" , "Sport Dwight Davis gave trophy for" , "McEnroe's game" .)