The most common and most likely answer to this crossword clue is the 6 letter word EPHORS
E
P
H
O
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S
Buddy explains!

The straight part
We know that "magistrates, as before" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case magistrates, as before = ephors.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 EPHORS mean?
EPHORS noun- One of the five annually-elected senior magistrates in various Dorian states, especially in ancient Sparta, where they oversaw the actions of Spartan kings.
- (in modern Greece) A superintendent or curator.