The most common and most likely answer to this crossword clue is the 7 letter word BACKBIT
I've seen this crossword clue in The Daily Telegraph
B
A
C
K
B
I
T
More clues leading to the result BACKBIT
Buddy explains!

The straight part
We know that "Said mean things about" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case said mean things about = backbit.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 BACKBIT mean?
BACKBIT verb- To make spiteful slanderous or defamatory statements about someone.
- To attack from behind or when out of earshot with spiteful or defamatory remarks.
- To speak badly of an absent individual.