The most common and most likely answer to this crossword clue is the 9 letter word INFECTION
I've seen this crossword clue in Financial Times
I
N
F
E
C
T
I
O
N
More clues leading to the result INFECTION
- Disease, in a manner of speaking, learner's overlooked
- Complaint among posh-sounding group?
- Little data on aroused state – about to go for coronavirus?
- Fine tonic cured disease
- Presence of virus; confine it somehow
- Division by 100 yielding finite number over 25
- Pants fit nice – no complaint
- One new story has Ecstasy displacing current virus possibly
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 = infection.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 INFECTION mean?
INFECTION noun- The act or process of infecting.
- An uncontrolled growth of harmful microorganisms in a host.