The most common and most likely answer to this crossword clue is the 9 letter word ENTERITIS
I've seen this crossword clue in The Times
E
N
T
E
R
I
T
I
S
More clues leading to the result ENTERITIS
- Venture into Microsoft's domain is trouble for corporation
- Tube complaint? It is on record
- One charging setter in criminal complaint
- Key that has been identified for problem inside?
- Inflammatory condition means record sex lives
- Tube complaint? It is put on record
- To begin with, it is an internal inflammation
- Record the other island’s disease
- Interest I developed in illness
- Doctor tries net to describe current inflammation
Buddy explains!

The straight part
We know that "complaint" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case complaint = enteritis.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 ENTERITIS mean?
ENTERITIS noun- Inflammation of the intestines, generally the small intestine, that may lead to diarrhea.