The most common and most likely answer to this crossword clue is the 3 plus 5 letter word MAN HOURS
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Buddy explains!
The straight part
We know that "Production units" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case production units = man hours.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 MAN HOURS mean?
MAN HOURS noun- The amount of work that can be done by one person in an hour.