The most common and most likely answer to this crossword clue is the 5 letter word NOYAU
N
O
Y
A
U
More clues leading to the result NOYAU
Buddy explains!

The straight part
We know that "Liqueur" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case liqueur = noyau.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 NOYAU mean?
NOYAU noun- A French liqueur made at Poissy in north central France from brandy and flavoured with almonds and the pits of apricots since the early nineteenth century.
- A social structure where individual animals live alone, but each male's territory overlaps with those of several females.