The most common and most likely answer to this crossword clue is the 13 letter word CONVALESCENTS
I've seen this crossword clue in The Daily Telegraph
C
O
N
V
A
L
E
S
C
E
N
T
S
Buddy explains!
The straight part
We know that "They’re not so bad as they have been" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they’re not so bad as they have been = convalescents.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 CONVALESCENTS mean?
CONVALESCENTS noun- A person recovering from illness.