The most common and most likely answer to this crossword clue is the 9 letter word DETECTION
I've seen this crossword clue in The Times
D
E
T
E
C
T
I
O
N
Buddy explains!

The straight part
We know that "making discovery" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case making discovery = detection.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 DETECTION mean?
DETECTION noun- The act of detecting or sensing something; discovering something that was hidden or disguised.
- The finding out of a constituent, a signal, an agent or the like, mostly by means of a specific device or method.