The most common and most likely answer to this crossword clue is the 9 letter word LONG-TERM
I've seen this crossword clue in The Guardian
L
O
N
G
-
T
E
R
M
Buddy explains!
The straight part
We know that "chronic" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chronic = long-term.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 LONG-TERM mean?
LONG-TERM adjective- Becoming evident after a relatively long time period.
- Extending over a relatively long time period.