The most common and most likely answer to this crossword clue is the 9 letter word TOOTHACHE
I've seen this crossword clue in Independent
T
O
O
T
H
A
C
H
E
More clues leading to the result TOOTHACHE
- Chewing hot taco, he gets this pain
- What causes pain, besides husband sporting facial hair?
- Steaming hot chocolate banishing depression and pain
- Honk horn, at first long- suffering
- Honk with laughter about helium
- Excessively stupid chat by the fellow – mouthy problem
- Furthermore, facial hair disguises husband’s affliction
- Trouble ahead – also hot during growth ahead
- Ooh, the cat is worried — it could be a canine problem
- Two rings interrupting wielding of hatchet is cause of pain
Buddy explains!
The straight part
We know that "it might need nitrous oxide" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case it might need nitrous oxide = toothache.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 TOOTHACHE mean?
TOOTHACHE noun- A pain or ache in a tooth.