The most common and most likely answer to this crossword clue is the 4 letter word HIYA
H
I
Y
A
Buddy explains!
The straight part
We know that "What’s heard in Yankee accent (see introductions)?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case what’s heard in yankee accent (see introductions)? = hiya.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 HIYA mean?
HIYA interjection- An informal greeting, hi, hello.
- A kiai, shouted as a limb is swung in attack.