The most common and most likely answer to this crossword clue is the 3 plus 6 plus 6 letter word AGE BEFORE BEAUTY
I've seen this crossword clue in Financial Times
A
G
E
B
E
F
O
R
E
B
E
A
U
T
Y
More clues leading to the result AGE BEFORE BEAUTY
Buddy explains!

The straight part
We know that "It’s said ironically to give precedence" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it’s said ironically to give precedence = age before beauty.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.