The most common and most likely answer to this crossword clue is the 8 letter word COARSENS
C
O
A
R
S
E
N
S
Buddy explains!

The straight part
We know that "Makes crude" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case makes crude = coarsens.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 COARSENS mean?
COARSENS verb- To make (more) coarse.
- To become (more) coarse.