The most common and most likely answer to this crossword clue is the 8 letter word QUEUEING
Q
U
E
U
E
I
N
G
Buddy explains!

The straight part
We know that "Waiting" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case waiting = queueing.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 QUEUEING mean?
QUEUEING verb- To put oneself or itself at the end of a waiting line.
- To arrange themselves into a physical waiting queue.
- To add to a queue data structure.
- To fasten the hair into a queue.
- The act of placing something in a queue.