The most common and most likely answer to this crossword clue is the 3 plus 5 letter word HOT WATER
I've seen this crossword clue in The Times
H
O
T
W
A
T
E
R
More clues leading to the result HOT WATER
- Possible boiler trouble
- Trouble perhaps brewing in this?
- Trouble — that's in the soup!
- Cooks throw tea into it to make trouble!
- Deployed to the war, causing trouble
- Having trouble in this sort of bottle
- Trouble bather gets into?
- A jam that’s required to make coffee
- Trouble on tap?
- Trouble that comes at bath time?
Buddy explains!

The straight part
We know that "trouble" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case trouble = hot water.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.