The most common and most likely answer to this crossword clue is the 9 letter word PROCREANT
I've seen this crossword clue in The Guardian
P
R
O
C
R
E
A
N
T
Buddy explains!
The straight part
We know that "Cor! Parent in the making?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cor! parent in the making? = procreant.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 PROCREANT mean?
PROCREANT noun- One who, or that which, procreates.
- That procreates.
- Of or pertaining to procreation; procreative.