The most common and most likely answer to this crossword clue is the 6 letter word EXTANT
I've seen this crossword clue in Financial Times
E
X
T
A
N
T
More clues leading to the result EXTANT
- Old lover with blemish — not one carrying on?
- Surviving navigational instrument with top missing
- Current navigational device not accommodating first polar direction
- Measuring device minus top still standing
- Surviving son leaves navigational instrument
- Surviving, once one is protected by explosive
- Surviving by hiding in a tent abroad
- Remaining aid to navigation has not succeeded
- Books on old soldiers still around
- Surviving Texan shot twin, dismissing victory
Buddy explains!

The straight part
We know that "Surviving" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case surviving = extant.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 EXTANT mean?
EXTANT adjective- Still in existence.
- Currently existing; not having disappeared.
- Still alive; not extinct.
- Standing out, or above the rest.