The most common and most likely answer to this crossword clue is the 3 plus 3 plus 2 letter word FLY ASH FL
F
L
Y
A
S
H
F
L
Buddy explains!
The straight part
We know that "some coal plant production" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case some coal plant production = fly ash fl.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.