The most common and most likely answer to this crossword clue is the 9 letter word SLEEPOVER
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Buddy explains!
The straight part
We know that "at friend's after having stayed the night?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case at friend's after having stayed the night? = sleepover.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 SLEEPOVER mean?
SLEEPOVER noun- The act of spending the night as a guest in another's house, especially when the participants are children.
- An overnight guest.