The most common and most likely answer to this crossword clue is the 6 letter word BLUISH
I've seen this crossword clue in Independent
B
L
U
I
S
H
More clues leading to the result BLUISH
- Go red about one displaying a different colour
- One in pink, somewhat different in colour?
- It’s fairly rude, and I go red outwardly
- Fairly colourful glow around India
- Turn red accepting one’s a bit obscene
- Looking slightly bruised, quite near the knuckle?
- Go red, welcoming indigo — as somewhat different hue?
- Reddening, one goes in shade
Buddy explains!

The straight part
We know that "It’s fairly rude" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it’s fairly rude = bluish.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 BLUISH mean?
BLUISH adjective- Having a tint or hue similar to the colour blue.
- Somewhat depressed; sad.