The most common and most likely answer to this crossword clue is the 8 letter word FEDAYEEN
I've seen this crossword clue in Financial Times
F
E
D
A
Y
E
E
N
More clues leading to the result FEDAYEEN
Buddy explains!

The straight part
We know that "commandos" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case commandos = fedayeen.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 FEDAYEEN mean?
FEDAYEEN noun- An Arab guerrilla or commando.