So get me one, I don’t care which of you does! (7)
I believe the answer is:
someone
'i don't care which of you does' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'so get me one' is the wordplay.
'get' is a charade indicator (letters next to each other).
'so'+'me'+'one'='SOMEONE'
Can you help me to learn more?
(Other definitions for someone that I've seen before include "big cheese" , "Unspecified human being" , "Celebrity" , "Important person" , "An unknown person" .)