The most common and most likely answer to this crossword clue is the 6 letter word KERNEL
I've seen this crossword clue in The Times
K
E
R
N
E
L
More clues leading to the result KERNEL
- Essence of report of army officer
- Sailors in part of ship, the centre
- Sailors boarding part of ship? That's it in a nutshell
- Nuts and bolts sailors fitted in part of ship
- Report of officer in centre of Brazil?
- Group of sailors cutting timber for ship's core
- Report of senior officer - a bit of a nut!
- Sailors in flat-bottomed boat showing heart
- Part of ship in which sailors stored grain
- . Sailors entering part of ship? That’s the important point
Buddy explains!

The straight part
We know that "Essence" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case essence = kernel.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 KERNEL mean?
KERNEL noun- The core, center, or essence of an object or system.
- The central (usually edible) part of a nut, especially once the hard shell has been removed.
- A single seed or grain, especially of corn or wheat.
- The stone of certain fruits, such as peaches or plums.
- A small mass around which other matter is concreted; a nucleus; a concretion or hard lump in the flesh.
- The central part of many computer operating systems which manages the system's resources and the communication between hardware and software components.
- The core engine of any complex software system.
- A function used to define an integral transform.
- A set of pairs of a mapping's domain which are mapped to the same value.
- For a given function (especially a linear map between vector spaces), the set of elements in the domain which are mapped to zero; (formally) given f : X → Y, the set {x ∈ X : f(x) = 0}.
- For a category with zero morphisms: the equalizer of a given morphism and the zero morphism which is parallel to that given morphism.
- (fuzzy set theory) The set of members of a fuzzy set that are fully included (i.e., whose grade of membership is 1).
- The human clitoris.
- The nucleus and electrons of an atom excluding its valence electrons.