The most common and most likely answer to this crossword clue is the 8 letter word REINVENT
I've seen this crossword clue in Financial Times
R
E
I
N
V
E
N
T
Buddy explains!

The straight part
We know that "coin again" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case coin again = reinvent.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 REINVENT mean?
REINVENT verb- To invent again something that has already been invented.
- To adapt into a different form; to give a new style or image to.