The most common and most likely answer to this crossword clue is the 9 letter word INCARNATE
I've seen this crossword clue in Financial Times
I
N
C
A
R
N
A
T
E
More clues leading to the result INCARNATE
- Instinctive to maintain vehicle In ultimate condition
- Perhaps driving north, goddess appearing in the flesh
- It’s essential to apprehend road user in the flesh
- As a person maybe driving north had lunch?
- Typified little girl being accepted into the responsibility of Social Services
- In a trance, bananas appear to be in possession of human qualities
- Typified certain changes including new article
- Triumph, say, in natural surroundings personified
- A certain creation eventually turning out in bodily form
- One can rant wildly, energy personified
Buddy explains!

The straight part
We know that "in the flesh" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in the flesh = incarnate.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 INCARNATE mean?
INCARNATE adjective- Embodied in flesh; given a bodily, especially a human, form; personified.
- Flesh-colored, crimson.
- To embody in flesh, invest with a bodily, especially a human, form.
- To incarn; to become covered with flesh, to heal over.
- To make carnal; to reduce the spiritual nature of.
- To put into or represent in a concrete form, as an idea.
- Not in the flesh; spiritual.