The most common and most likely answer to this crossword clue is the 6 letter word RIDGES
I've seen this crossword clue in Financial Times
R
I
D
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More clues leading to the result RIDGES
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The straight part
We know that "wrinkles" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wrinkles = ridges.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 RIDGES mean?
RIDGES noun- The back of any animal; especially the upper or projecting part of the back of a quadruped.
- Any extended protuberance; a projecting line or strip.
- The line along which two sloping surfaces meet which diverge towards the ground.
- The highest point on a roof, represented by a horizontal line where two roof areas intersect, running the length of the area.
- (fortifications) The highest portion of the glacis proceeding from the salient angle of the covered way.
- A chain of mountains.
- A chain of hills.
- A long narrow elevation on an ocean bottom.
- An elongated region of high atmospheric pressure.