The most common and most likely answer to this crossword clue is the 8 letter word OATCAKES
I've seen this crossword clue in The Guardian
O
A
T
C
A
K
E
S
Buddy explains!

The straight part
We know that "biscuits/biscuits" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case biscuits/biscuits = oatcakes.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 OATCAKES mean?
OATCAKES noun- Any of many flat biscuits, or cakes, made from oatmeal.