The most common and most likely answer to this crossword clue is the 6 letter word STOUPS
S
T
O
U
P
S
Buddy explains!

The straight part
We know that "vessels in church" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vessels in church = stoups.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 STOUPS mean?
STOUPS noun- A bucket.
- A mug or drinking vessel.
- A receptacle for holy water, especially a basin set at the entrance of a church.