Real sort of nobleman (4)
I believe the answer is:
earl
'nobleman' is the definition.
(member of the nobility)
'real sort' is the wordplay.
'sort' indicates an anagram.
'real' is an anagram of 'EARL'.
'of' acts as a link.
(Other definitions for earl that I've seen before include "Male member of British nobility" , "Husband of a countess" , "British peer and Dublin street" , "Peer of the realm" , "Jimmy Carter's middle name" .)