Mother and Yankee have spoken of local dignitary (7)
I believe the answer is:
mayoral
'of local dignitary' is the definition.
(relating to a mayor)
'mother and yankee have spoken' is the wordplay.
'mother' becomes 'ma' (ma can mean mother).
'and' means one lot of letters go next to another.
'yankee' becomes 'Y' (phonetic alphabet: alpha, bravo, charlie etc.).
'have' is a charade indicator (letters next to each other).
'spoken' becomes 'oral' (similar in meaning).
'ma'+'y'+'oral'='MAYORAL'
(Other definitions for mayoral that I've seen before include "Dignitary's" , "Of a civic dignitary" , "for chief councillor?" , "town office" , "for local official" .)