The most common and most likely answer to this crossword clue is the 5 plus 6 letter word FEMME FATALE
I've seen this crossword clue in The Times
F
E
M
M
E
F
A
T
A
L
E
More clues leading to the result FEMME FATALE
Buddy explains!
The straight part
We know that "Woman captivating fellow primarily in the flesh?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case woman captivating fellow primarily in the flesh? = femme fatale.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.