The most common and most likely answer to this crossword clue is the 8 letter word CRACKNEL
I've seen this crossword clue in The Guardian
C
R
A
C
K
N
E
L
More clues leading to the result CRACKNEL
Buddy explains!
The straight part
We know that "biscuit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case biscuit = cracknel.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 CRACKNEL mean?
CRACKNEL noun- A hard, crisp biscuit
- (in the plural) crackling (fried pork fat)