The most common and most likely answer to this crossword clue is the 7 letter word WAKEFUL
I've seen this crossword clue in The Times
W
A
K
E
F
U
L
More clues leading to the result WAKEFUL
Buddy explains!

The straight part
We know that "Not getting off" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not getting off = wakeful.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 WAKEFUL mean?
WAKEFUL adjective- Awake; not sleeping.
- Sleepless.
- Vigilant and alert; watchful.