Upset real toff (4)
I believe the answer is:
earl
'toff' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'upset real' is the wordplay.
'upset' indicates anagramming the letters.
'real' anagrammed gives 'EARL'.
Can you help me to learn more?
(Other definitions for earl that I've seen before include "Rank below marquess" , "Husband of a countess" , "Essex, say" , "Countess his wife" , "Male member of British nobility" .)