The most common and most likely answer to this crossword clue is the 8 plus 4 letter word KILOWATT HOUR
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More clues leading to the result KILOWATT HOUR
Buddy explains!
The straight part
We know that "Energy unit" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case energy unit = kilowatt hour.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 KILOWATT HOUR mean?
KILOWATT HOUR noun- A unit of energy equal to that done by one kilowatt acting for one hour