The most common and most likely answer to this crossword clue is the 8 letter word GLYCEROL
I've seen this crossword clue in The Times
G
L
Y
C
E
R
O
L
Buddy explains!
The straight part
We know that "sweet stuff" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sweet stuff = glycerol.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 GLYCEROL mean?
GLYCEROL noun- 1,2,3-trihydroxy-propane or propan-1,2,3-triol; a trihydric alcohol
- A syrupy sweet liquid obtained as a by-product in the manufacture of soap from animal or vegetable oils and fats; it is used as an antifreeze, a plasticizer, and a food sweetener and in the manufacture of dynamite, cosmetics etc.