The most common and most likely answer to this crossword clue is the 6 letter word ENTITY
I've seen this crossword clue in Financial Times
E
N
T
I
T
Y
More clues leading to the result ENTITY
- Object songbird found in English city
- Body: it’s what was right inside doorway
- About to leave the whole thing
- Body and sense of self I’d ignored
- Body essence
- Body essence
- Being included in document I type
- Being who I am, I had to leave
- A thing made from tin yet to be modified
- A complete lot shunning tips for respectable existence
Buddy explains!

The straight part
We know that "existence" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case existence = entity.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 ENTITY mean?
ENTITY noun- That which has a distinct existence as an individual unit. Often used for organisations which have no physical form.
- The existence of something considered apart from its properties.
- Anything about which information or data can be stored in a database; in particular, an organised array or set of individual elements or parts.
- The state or quality of being or existence.
- A spirit, ghost, or the like.
- An alien lifeform that has no corporeal body.