The most common and most likely answer to this crossword clue is the 10 letter word MANSERVANT
I've seen this crossword clue in The Daily Telegraph
M
A
N
S
E
R
V
A
N
T
Buddy explains!

The straight part
We know that "Domestic help" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case domestic help = manservant.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 MANSERVANT mean?
MANSERVANT noun- A male servant.