Person who might bring you up in simple row (9)
I believe the answer is:
plaintiff
'person who might bring you up' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
'simple row' is the wordplay.
'simple' becomes 'plain' (associated in meaning).
'row' becomes 'tiff' (tiff is a kind of row).
'plain'+'tiff'='PLAINTIFF'
'in' is the link.
Can you help me to learn more?
(Other definitions for plaintiff that I've seen before include "One bringing legal case" , "The one taking the court action" , "he goes to court" , "Temporary disappearances of a heavenly body" , "one prompting action" .)