The most common and most likely answer to this crossword clue is the 4 letter word COGS
I've seen this crossword clue in The Daily Telegraph
C
O
G
S
Buddy explains!
The straight part
We know that "underlings" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case underlings = cogs.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 COGS mean?
COGS noun- A tooth on a gear.
- A gear; a cogwheel.
- An unimportant individual in a greater system.
- A projection or tenon at the end of a beam designed to fit into a matching opening of another piece of wood to form a joint.
- One of the rough pillars of stone or coal left to support the roof of a mine.
- A ship of burden, or war with a round, bulky hull.
- A trick or deception; a falsehood.
- A small fishing boat.
- A small round wooden vessel for holding milk.