The most common and most likely answer to this crossword clue is the 6 letter word BEDPAN
I've seen this crossword clue in The Guardian
B
E
D
P
A
N
More clues leading to the result BEDPAN
- What Syrinx refused to do, but Selene did, in hospital vessel
- Patient dropping in here unrobed, panicking nurse
- Be patient at first and perhaps you might get to go in it
- Some dubbed pandemic ‘potty‘
- Old man housed in unfinished Denby development was warmer before retirement
- Shallow vessel to move across under bottom
Buddy explains!

The straight part
We know that "Shallow vessel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case shallow vessel = bedpan.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 BEDPAN mean?
BEDPAN noun- A pan used for urination and defecation while in bed, now usually for reasons of medical necessity or convenience.