The most common and most likely answer to this crossword clue is the 10 letter word ALTARPIECE
I've seen this crossword clue in The Times
A
L
T
A
R
P
I
E
C
E
Buddy explains!
The straight part
We know that "work of art in church" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case work of art in church = altarpiece.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 ALTARPIECE mean?
ALTARPIECE noun- A work of art suspended above and behind an altar in a church