The most common and most likely answer to this crossword clue is the 11 letter word UNCIVILISED
I've seen this crossword clue in The Times
U
N
C
I
V
I
L
I
S
E
D
Buddy explains!
The straight part
We know that "Boorish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case boorish = uncivilised.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 UNCIVILISED mean?
UNCIVILISED adjective- Crude, barbarous, wild, uncultured.
- Used to describe people who display a marked lack of manners as defined by a given culture.
- Used to describe behaviours deemed savage or inappropriate.