The most common and most likely answer to this crossword clue is the 8 letter word CAFFEINE
C
A
F
F
E
I
N
E
More clues leading to the result CAFFEINE
- In restaurant’s fine-ground stimulant
- Roughly forces a German to provide stimulant
- Drug gets boss out of his box during film
- A very loud, funny niece about to provide reviver
- Grass-covered sort of fife: it may produce a buzz
- Alkaloid found when fiancée, after travelling, consumed food at first
- Coffee shop receives fine after distributing legal high
Buddy explains!

The straight part
We know that "Alkaloid" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case alkaloid = caffeine.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 CAFFEINE mean?
CAFFEINE noun- An alkaloid, C8H10N4O2, found naturally in tea and coffee plants which acts as a mild stimulant on the central nervous system.