The most common and most likely answer to this crossword clue is the 7 letter word DEAREST
I've seen this crossword clue in The Guardian
D
E
A
R
E
S
T
More clues leading to the result DEAREST
- Most expensive honey
- Love is almost dead — what’s left?
- Potentially the cause of most damage inside a restaurant
- Requiring maximum amount of cash, honey
- Beloved abandoning first notion to settle
- Some of multitude are strangely most excessive
- Darling daughter, serious but heartless
- Most expensive sort of address?
- It’s most expensive, darling
Buddy explains!

The straight part
We know that "Potentially the cause of most damage" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case potentially the cause of most damage = dearest.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 DEAREST mean?
DEAREST adjective- High in price; expensive.
- Loved; lovable.
- Loving, affectionate, heartfelt
- Precious to or greatly valued by someone.
- A formal way to start (possibly after my) addressing somebody at the beginning of a letter, memo etc.
- A formal way to start (often after my) addressing somebody one likes or regards kindly.
- An ironic way to start (often after my) addressing an inferior.
- Noble.
- A beloved person; a term of endearment.