The most common and most likely answer to this crossword clue is the 9 letter word ANCESTRAL
A
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More clues leading to the result ANCESTRAL
- Lancaster ground inherited from one’s forebears
- New cast learn of predecessors
- A new king in rebuilt castle of family line
- A new claret’s ordered – typical of some stately homes?
- Inherited bric-a-brac finally in a home artist left
- Describing one’s descent from Lancaster
- Lancaster’s illegitimate according to inheritance
- Hereditary earls can’t, unfortunately
- Inherited Lancaster’s mess
- Family trips not starting, I abandon path
Buddy explains!

The straight part
We know that "associated with ancient families" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case associated with ancient families = ancestral.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ANCESTRAL mean?
ANCESTRAL adjective- Of, pertaining to, derived from, or possessed by, an ancestor or ancestors