The most common and most likely answer to this crossword clue is the 4 letter word EYRE
E
Y
R
E
Buddy explains!
The straight part
We know that "Jane" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case jane = eyre.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 EYRE mean?
EYRE noun- A journey in circuit of certain itinerant judges called justices in eyre (or in itinere).