The most common and most likely answer to this crossword clue is the 5 letter word FELID
F
E
L
I
D
Buddy explains!
The straight part
We know that "Sex?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sex? = felid.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 FELID mean?
FELID noun- Any member of the cat family (Felidae).