The most common and most likely answer to this crossword clue is the 3 letter word BUN
I've seen this crossword clue in The Times
B
U
N
More clues leading to the result BUN
Buddy explains!

The straight part
We know that "Cake" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cake = bun.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 BUN mean?
BUN noun- A small bread roll, often sweetened or spiced.
- A tight roll of hair worn at the back of the head.
- A cupcake.
- A drunken spree.
- A newbie.
- (chiefly in the plural) A buttock.
- Vagina
- A rabbit or sometimes a squirrel.
- Marijuana cigarette, joint
- To smoke cannabis.
- To shoot.
- A Korean unit of length equivalent to about 0.3 cm.