The most common and most likely answer to this crossword clue is the 7 letter word AREOLAE
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Buddy explains!
The straight part
We know that "coloured rings" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case coloured rings = areolae.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 AREOLAE mean?
AREOLAE noun- The colored circle around a nipple, more exactly known as areola mammae.
- Any small circular area that is different from its immediate environment, such as the colored ring around the pupil of the eye (iris) or an inflamed region surrounding a pimple.
- Any of the small spaces throughout areolar connective tissue.