The most common and most likely answer to this crossword clue is the 8 letter word PROVERBS
I've seen this crossword clue in Independent
P
R
O
V
E
R
B
S
More clues leading to the result PROVERBS
- Professional words in religious book
- Further note about dog breeder’s first book
- Show bank book
- Book show supported by bank
- Favouring certain words in an old book
- In favour of words revealing actions in an old book
- More than one saw book of the Old Testament
- This book‘s in favour of look and say for example
- Book where dog wears lead on Sunday (8
- Words of 3 for doing words
Buddy explains!

The straight part
We know that "an old book" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case an old book = proverbs.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 PROVERBS mean?
PROVERBS noun- A phrase expressing a basic truth which may be applied to common situations.
- A striking or paradoxical assertion; an obscure saying; an enigma; a parable.
- A familiar illustration; a subject of contemptuous reference.
- A drama exemplifying a proverb.
- To write or utter proverbs.
- To name in, or as, a proverb.
- To provide with a proverb.