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

The straight part
We know that "Servant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case servant = handmaid.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 HANDMAID mean?
HANDMAID noun- A maid that waits at hand; a female servant or attendant.