In which to possibly score about a hundred? (6)
I believe the answer is:
soccer
'in which' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'possibly score about a hundred?' is the wordplay.
'possibly' is an anagram indicator.
'about' means one lot of letters goes inside another.
'a hundred?' becomes 'c' (Roman numerals).
'score' is an anagram of 'socer'.
'socer' going around 'c' is 'SOCCER'.
'to' is the link.
Can you help me to learn more?
(Other definitions for soccer that I've seen before include "Ball game" , "Roy Keane's game" , "Association football" , "Informally, game" , "popular game" .)