The most common and most likely answer to this crossword clue is the 9 letter word IMPACTING
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Buddy explains!

The straight part
We know that "Making a difference" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case making a difference = impacting.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 IMPACTING mean?
IMPACTING verb- To collide or strike, the act of impinging.
- To compress; to compact; to press into something or pack together.
- To influence; to affect; to have an impact on.
- To stamp or impress onto something.