The most common and most likely answer to this crossword clue is the 6 letter word VIGILS
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More clues leading to the result VIGILS
Buddy explains!

The straight part
We know that "night services" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case night services = vigils.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 VIGILS mean?
VIGILS noun- An instance of keeping awake during normal sleeping hours, especially to keep watch or pray.
- A period of observation or surveillance at any hour.
- The eve of a religious festival in which staying awake is part of the ritual devotions.
- A quiet demonstration in support of a cause.