The most common and most likely answer to this crossword clue is the 4 plus 7 letter word BANK MANAGER
I've seen this crossword clue in The Times
B
A
N
K
M
A
N
A
G
E
R
More clues leading to the result BANK MANAGER
Buddy explains!
The straight part
We know that "Professional in finance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case professional in finance = bank manager.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.