Revered personages, but they might have been dud, sir (6)
I believe the answer is:
druids
'revered personages' is the definition.
The definition and answer can be both people as well as being plural nouns.
Maybe you can see a link between them that I can't see?
'they might have been dud sir' is the wordplay.
'dud sir' can be anagrammed to 'DRUIDS'.
But, I'm not sure how this is indicated.
'but' acts as a link.
Can you help me to learn more?
(Other definitions for druids that I've seen before include "Ancient Celtic priests" , "Celtic priests of old" , "Pre-Christian Celtic priests" , "Ancient priests of Wales" , "Ancient Welsh and Irish priests" .)