The most common and most likely answer to this crossword clue is the 10 letter word PASTORATES
I've seen this crossword clue in The Guardian
P
A
S
T
O
R
A
T
E
S
Buddy explains!

The straight part
We know that "groups of clergymen" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case groups of clergymen = pastorates.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 PASTORATES mean?
PASTORATES noun- The role or responsibilities of a pastor.
- The period of service of a particular pastor to their congregation; their term of office.
- An organization or body consisting of multiple pastors.