The most common and most likely answer to this crossword clue is the 2 plus 4 letter word NO SHOW
I've seen this crossword clue in The Guardian
N
O
S
H
O
W
More clues leading to the result NO SHOW
- Person not turning up food or water, initially
- Failure to appear in numbers; in what way?
- Failure to attend meal — that hurts
- Absentee gets meals with old women
- Small numbers — in what way is that something bothering restaurant?
- One failing to attend meal — ring wife
- Food that is a source of discomfort! One keeps away
Buddy explains!

The straight part
We know that "Failure to attend" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case failure to attend = no show.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 NO SHOW mean?
NO SHOW noun- An absence; failure to show up or to make a scheduled appearance, especially at a hotel or a place of employment.
- A person or group that does not show up.
- To fail to show up for something.