The most common and most likely answer to this crossword clue is the 16 letter word RETURNÂ TOÂ SENDER
I've seen this crossword clue in The Guardian
R
E
T
U
R
N
Â
T
O
Â
S
E
N
D
E
R
Buddy explains!

The straight part
We know that "chart hit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chart hit = return to sender.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.