Fortune derived from rich ancestors (6)
I believe the answer is:
chance
'fortune' is the definition.
(I know that fortune can be written as chance)
'derived from rich ancestors' is the wordplay.
'derived from' indicates a hidden word.
'CHANCE' is hidden in the letters of 'rich ancestors'.
(Other definitions for chance that I've seen before include "Likelihood" , "The way things happen, luck" , "Accidental; opportunity" , "I wish (but it won't happen!)" , "Lady luck" .)