The most common and most likely answer to this crossword clue is the 7 letter word SWARTHY
I've seen this crossword clue in The Guardian
S
W
A
R
T
H
Y
More clues leading to the result SWARTHY
- Skin disfigurement concealed in pitch black
- Dark pitch masking blemish
- Brown hesitant about growth
- Why rats could be dark-looking
- Dark-coloured blemish one’s reluctant to talk about
- Creative injecting heroin after second whisky gets dark
- Embarrassed about growth getting dark
- Dark imperfection in Bashful
- What's ruddy-skinned? Wrong!
- Nervy around people, hiding blemish that’s dark
Buddy explains!

The straight part
We know that "Brown" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case brown = swarthy.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 SWARTHY mean?
SWARTHY noun- A swarthy person.
- Tawny, dusky, dark.
- Dark-skinned.
- Darker-skinned than white, but lighter-skinned than tawny.
- Evil, malicious.
- Weathered, rough.