The most common and most likely answer to this crossword clue is the 9 letter word SEPTUPLET
I've seen this crossword clue in The Guardian
S
E
P
T
U
P
L
E
T
More clues leading to the result SEPTUPLET
Buddy explains!
The straight part
We know that "A seventh part of labour production" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a seventh part of labour production = septuplet.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 SEPTUPLET mean?
SEPTUPLET noun- One of a group of seven babies born at the same birth.
- A tuplet of seven notes.