The most common and most likely answer to this crossword clue is the 4 letter word STYX
I've seen this crossword clue in The Guardian
S
T
Y
X
More clues leading to the result STYX
- Underground river no longer flows from the mouth
- Underworld river remains audible
- Rod’s called out in hellish water
- Rod’s announced hellish setting for Sailing
- Batons in audition that you will finally pass across?
- Bits of wood reported in hellish river
- River finally crossed where pigs are unknown
- Reportedly stays late crossing it
- Vacant seat unknown by fabulous river
- Twigs picked up from river
Buddy explains!
The straight part
We know that "that you will finally pass across?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case that you will finally pass across? = styx.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.