The most common and most likely answer to this crossword clue is the 9 letter word ENDORPHIN
I've seen this crossword clue in Financial Times
E
N
D
O
R
P
H
I
N
More clues leading to the result ENDORPHIN
- Object to alternative level of acid in painkiller
- Upper Rhine pond suffers pollution
- Hormone in hen — products not half contaminated
- No diner gets order around pub — it could produce a rush!
- Ponder varying hydrogen in body chemical
- Pain suppressant, one for a parentless child, given on purpose
- Send for GP to get pain-killer
- Dodgily roped in to swallow hot new painkiller
- Crackpot phoned in to obtain queen’s personal number
Buddy explains!

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 ENDORPHIN mean?
ENDORPHIN noun- Any of a group of peptide hormones found in the brain that act as neurotransmitters and have properties similar to morphine.