The most common and most likely answer to this crossword clue is the 8 letter word UNTANGLE
I've seen this crossword clue in Independent
U
N
T
A
N
G
L
E
More clues leading to the result UNTANGLE
- Work out one approach lacking information
- 3 briefly confused about name of brush
- Work out what’s caught by weasel — gnat numbers seen rising
- Sort out university book collection corner
- Extricate from fashionable National maze
- Straighten out the relative becoming vitamin-deficient after ingesting an insect from the east
Buddy explains!

The straight part
We know that "brush" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case brush = untangle.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 UNTANGLE mean?
UNTANGLE verb- To remove tangles or knots from.
- (by extension) To remove confusion or mystery from.