The most common and most likely answer to this crossword clue is the 8 letter word COLONISE
I've seen this crossword clue in The Guardian
C
O
L
O
N
I
S
E
More clues leading to the result COLONISE
Buddy explains!
The straight part
We know that "to settle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to settle = colonise.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 COLONISE mean?
COLONISE verb- To settle (a place) with colonists, and hence make (a place) into a colony.
- To settle (a group of people, a species, or the like) in a place as a colony.
- To settle among and establish control over (the indigenous people of an area).
- To begin a colony or colonies.
- (by extension) To intrude into and take over (the autonomy, experience, social movement, etc, of a less powerful person or group); to commandeer or appropriate.