The most common and most likely answer to this crossword clue is the 3 letter word AIL
I've seen this crossword clue in Financial Times
A
I
L
More clues leading to the result AIL
- Regular occurrences of racial trouble
- Trouble in parliament from the right
- Trouble when leader vacates post
- Be sick, spitting out fermented beer?
- Beer reportedly makes you sicken
- Worry, hearing mention of alcoholic drink
- Unopened post creates trouble
- Beer they say makes you sicken
- Detective losing head creates trouble
- Detective losing head could create trouble
Buddy explains!

The straight part
We know that "troubl" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case troubl = ail.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 AIL mean?
AIL noun- An ailment; trouble; illness.
- To cause to suffer; to trouble, afflict. (Now chiefly in interrogative or indefinite constructions.)
- To be ill; to suffer; to be troubled.
- Painful; troublesome.
- The awn of barley or other types of corn.