The most common and most likely answer to this crossword clue is the 1 plus 5 plus 3 letter word A TOUGH ASK
I've seen this crossword clue in Independent
A
T
O
U
G
H
A
S
K
Buddy explains!
The straight part
We know that "A job detaining out-of-head violent type?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a job detaining out-of-head violent type? = a tough ask.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.