Dignified female author holding sway (7)
I believe the answer is:
dowager
'dignified female' is the definition.
(dowager can informally mean a dignified old woman)
'author holding sway' is the wordplay.
'author' becomes 'doer' (both can mean the person who causes something).
'holding' is an insertion indicator.
'sway' becomes 'wag'.
'doer' going around 'wag' is 'DOWAGER'.
(Other definitions for dowager that I've seen before include "Dignified (or wealthy) elderly woman" , "old lady" , "woman of status" , "Titled widow" , "Woman who holds title from dead husband" .)