The most common and most likely answer to this crossword clue is the 6 plus 9 letter word CARNAL KNOWLEDGE
I've seen this crossword clue in Financial Times
C
A
R
N
A
L
K
N
O
W
L
E
D
G
E
More clues leading to the result CARNAL KNOWLEDGE
Buddy explains!

The straight part
We know that "it" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it = carnal knowledge.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.