The most common and most likely answer to this crossword clue is the 7 letter word BLOOMER
I've seen this crossword clue in The Sunday Telegraph
B
L
O
O
M
E
R
Buddy explains!
The straight part
We know that "Baker’s mistake?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case baker’s mistake? = bloomer.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 BLOOMER mean?
BLOOMER noun- An ironworker.
- A minor or embarrassing mistake with minimal results.
- A circular loaf of white bread.
- A blooming flower.
- One who blooms, matures, or develops.
- A costume for women, consisting of a short dress with loose trousers gathered around the ankles, and often a broad-brimmed hat.
- A woman who wears a Bloomer costume.