The most common and most likely answer to this crossword clue is the 9 letter word REINHABIT
I've seen this crossword clue in The Daily Telegraph
R
E
I
N
H
A
B
I
T
More clues leading to the result REINHABIT
Buddy explains!
The straight part
We know that "Once more live in" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case once more live in = reinhabit.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 REINHABIT mean?
REINHABIT verb- To inhabit again (after living elsewhere)