The most common and most likely answer to this crossword clue is the 6 letter word SIESTA
I've seen this crossword clue in Independent
S
I
E
S
T
A
More clues leading to the result SIESTA
- Nap in noisiest apartment
- Seat is arranged for rest of the afternoon
- Sleep — that is one way to interrupt it
- Rickety seat is used for afternoon nap
- Aussie state nurses rest in the heat
- Rest as site's revamped
- Tea is prepared after son's afternoon nap
- Rest as site out of order
- Seat is ordered for afternoon nap
- A short nap in Susie’s tavern
Buddy explains!

The straight part
We know that "Nap" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nap = siesta.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 SIESTA mean?
SIESTA noun- A nap, especially an afternoon one taken after lunch in some cultures.
- To take a siesta; to nap.