The most common and most likely answer to this crossword clue is the 7 plus 5 letter word PERSONA GRATA
I've seen this crossword clue in Independent
P
E
R
S
O
N
A
G
R
A
T
A
Buddy explains!
The straight part
We know that "Someone favoured" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case someone favoured = persona grata.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.