The most common and most likely answer to this crossword clue is the 9 letter word NEURALGIA
I've seen this crossword clue in The Guardian
N
E
U
R
A
L
G
I
A
More clues leading to the result NEURALGIA
- Rule again, suffering spasmodic pain
- Broken rule again produces intermittent pain
- Bully regularly in a rage suffering spasmodic pain
- Severe pain sends tormented Algerian round the bend
- Pain of north European country losing monarch
- Rule again broken, resulting in complaint
- Dissolve a granule with iodine for this?
- Suffering nerves in northern Europe, ruler having left country
- This nervous problem, strangely, could be inarguable if bishop’s on board
- Pain again with ruler, endlessly thrashed
Buddy explains!

The straight part
We know that "Severe pain" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case severe pain = neuralgia.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 NEURALGIA mean?
NEURALGIA noun- An acute, severe, intermittent pain that radiates along a nerve.