The most common and most likely answer to this crossword clue is the 8 letter word WARLORDS
I've seen this crossword clue in Financial Times
W
A
R
L
O
R
D
S
Buddy explains!

The straight part
We know that "belligerent types" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case belligerent types = warlords.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 WARLORDS mean?
WARLORDS noun- A high military officer in a warlike nation.
- A local ruler or bandit leader usually where the government is weak.