The most common and most likely answer to this crossword clue is the 8 letter word CORRECTS
I've seen this crossword clue in Financial Times
C
O
R
R
E
C
T
S
Buddy explains!

The straight part
We know that "Uses white fluid" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case uses white fluid = corrects.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 CORRECTS mean?
CORRECTS verb- To make something that was wrong become right; to remove error from.
- (by extension) To grade (examination papers).
- To inform (someone) of their error.
- To discipline; to punish.