The most common and most likely answer to this crossword clue is the 3 letter word YET
I've seen this crossword clue in The Guardian
Y
E
T
More clues leading to the result YET
- Still one escapes Himalayan monster
- By now cryptid must be finally dismissed
- Mythical creature doesn't have one on the other hand
- Monstrous creature -- one not spotted nevertheless
- Still, every memorable event ends
- Still legendary creature’s not completely visible
- In Moscow, no nationalist has been expelled so far
- Salt Lake City all ends up, still
- …even so, the elusive creature didn’t finish
- 50% of 20 or 80 or 90? All the same?
Buddy explains!

The straight part
We know that "still" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case still = yet.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 YET mean?
YET adverb- (usually with negative) Thus far; up to the present; up to some specified time; still
- Continuously up to the current time; still.
- At some future time; eventually; still.
- (after certain copulative verbs, followed by an infinitive) Not as of the time referenced.
- In addition.
- (degree) Even.
- Nevertheless; however; but; despite that.
- A metal pan or boiler; yetling.
- To melt; found; cast, as metal.
- To get.