The most common and most likely answer to this crossword clue is the 8 letter word EPIDURAL
I've seen this crossword clue in The Times
E
P
I
D
U
R
A
L
More clues leading to the result EPIDURAL
- Back-stabber has drag artist clutching lower back
- A riled up drunk gets painkiller
- Feeling duller at end of term?
- Dial up re being feverish, wanting relief from labour
- Drag artist about to fade, turning up for number
- A number, with minimum of effort, swim up river
- Dupe/liar misused a drug
- Recording personal details, Laura shortly arranged anaesthetic
Buddy explains!

The straight part
We know that "Back-stabber" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case back-stabber = epidural.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 EPIDURAL mean?
EPIDURAL noun- An injection of anaesthetic into the epidural space of the spine, especially associated with pain relief during childbirth.
- Situated on or outside the dura mater.