The most common and most likely answer to this crossword clue is the 9 plus 6 letter word SUFFRAGAN BISHOP
I've seen this crossword clue in Financial Times
S
U
F
F
R
A
G
A
N
B
I
S
H
O
P
Buddy explains!
The straight part
We know that "a man of God" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a man of god = suffragan bishop.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.