Horses said to be dignitaries (6)
I believe the answer is:
mayors
'be dignitaries' is the definition.
(I have seen 'Local dignitaries ' mean 'mayors' so perhaps 'dignitaries' could also mean 'mayors')
I can't explain the remainder of the clue.
(Other definitions for mayors that I've seen before include "Town officials" , "Civic leaders" , "Head of city governments" , "Local dignitaries" , "Municipal leaders" .)