The most common and most likely answer to this crossword clue is the 7 letter word UNCIVIL
U
N
C
I
V
I
L
More clues leading to the result UNCIVIL
Buddy explains!

The straight part
We know that "rude" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rude = uncivil.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 UNCIVIL mean?
UNCIVIL adjective- Not civilized
- Not civil; discourteous; impolite