The most common and most likely answer to this crossword clue is the 10 letter word BARBARIANS
I've seen this crossword clue in The Sunday Telegraph
B
A
R
B
A
R
I
A
N
S
Buddy explains!
The straight part
We know that "uncivilised lot" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case uncivilised lot = barbarians.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 BARBARIANS mean?
BARBARIANS noun- A non-Greek or a non-Roman.
- An uncivilized or uncultured person, originally compared to the hellenistic Greco-Roman civilisation; often associated with fighting or other such shows of strength.
- Someone from a developing country or backward culture.
- A warrior, clad in fur or leather, associated with sword and sorcery stories.
- A person destitute of culture; a Philistine.
- A cruel, savage, brutal person; one without pity or humanity.
- A foreigner, especially with barbaric qualities as in the above definitions.