The most common and most likely answer to this crossword clue is the 8 letter word EYESPOTS
E
Y
E
S
P
O
T
S
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The straight part
We know that "Butterfly markings" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case butterfly markings = eyespots.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 EYESPOTS mean?
EYESPOTS noun- Any of various primitive light-sensitive organs or regions in many diverse organisms.
- An eye-like marking on the tail of a peacock or the wing of a butterfly.
- Any of a group of fungal infections of grasses that are characterized by oval spots; strawbreaker