The most common and most likely answer to this crossword clue is the 4 plus 3 letter word TOBY JUG
T
O
B
Y
J
U
G
More clues leading to the result TOBY JUG
- Mug Times sent into closed prison
- Drinking vessel that could bring ultimately nothing but joy
- Mug finding something amusing about British prison
- For sale, non-uniform prison tankard
- Man goes to prison for drinking
- For sale: can and mug
- Boyfriend, initially visiting model prison, brings pot
- Vessel closed near prison
- Pot for salebeside prison
Buddy explains!

The straight part
We know that "Vessel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vessel = toby jug.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.