The most common and most likely answer to this crossword clue is the 8 letter word SMUDGING
I've seen this crossword clue in The Times
S
M
U
D
G
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Buddy explains!

The straight part
We know that "Making Mark" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case making mark = smudging.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 SMUDGING mean?
SMUDGING verb- To obscure by blurring; to smear.
- To soil or smear with dirt.
- To use dense smoke to protect from insects.
- To stifle or smother with smoke.
- To burn herbs as a cleansing ritual (suffumigation).
- To subject to ritual burning of herbs (suffumigation, smudging).
- The act of something being smudged.
- A stain or smear left by something being smudged.
- Suffumigation.