The most common and most likely answer to this crossword clue is the 7 letter word CANARDS
I've seen this crossword clue in The Daily Telegraph
C
A
N
A
R
D
S
Buddy explains!
The straight part
We know that "False rumours" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case false rumours = canards.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 CANARDS mean?
CANARDS noun- A false or misleading report or story, especially if deliberately so.
- A type of aircraft in which the primary horizontal control and stabilization surfaces are in front of the main wing.
- Any small winglike structure on a vehicle, usually used for stabilization.