Nobleman in tavern changed note (7)
I believe the answer is:
baronet
'nobleman' is the definition.
(I know that baronet is a type of baron)
'tavern changed note' is the wordplay.
'tavern' becomes 'bar' (I've seen this before).
'changed' is an anagram indicator.
'note' with letters rearranged gives 'onet'.
'bar'+'onet'='BARONET'
'in' is the link.
(Other definitions for baronet that I've seen before include "Member of the British order of honour" , "A Bronte (anag.)" , "One's entitled" , "Sir Somebody-or-other?" , "Nobleman" .)