The most common and most likely answer to this crossword clue is the 10 letter word FRANCISCAN
I've seen this crossword clue in The Sunday Telegraph
F
R
A
N
C
I
S
C
A
N
More clues leading to the result FRANCISCAN
Buddy explains!
The straight part
We know that "person in order to follow vocation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case person in order to follow vocation = franciscan.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.