The most common and most likely answer to this crossword clue is the 5 letter word ANIME
I've seen this crossword clue in Independent
A
N
I
M
E
Buddy explains!

The straight part
We know that "cartoon style" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cartoon style = anime.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 ANIME mean?
ANIME noun- An artistic style originating in, and associated with, Japanese animation, and that has also been adopted by a comparatively low number of animated works from other countries.
- An animated work that originated in Japan, regardless of the artistic style.
- An animated work, regardless of the country of origin.
- The resin of the courbaril (Hymenaea courbaril), used in varnishes.