The most common and most likely answer to this crossword clue is the 7 letter word GASBAGS
I've seen this crossword clue in The Daily Telegraph
G
A
S
B
A
G
S
More clues leading to the result GASBAGS
Buddy explains!
The straight part
We know that "They are" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they are = gasbags.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 GASBAGS mean?
GASBAGS noun- A bag or bladder to hold a reservoir of gas, as in a hot-air balloon.
- A person who is overly garrulous or prone to making empty, unsupportable statements; a windbag.