Crossword Genius

Slight difficulties if Romeo cracks shellfish (8)

Ross

I believe the answer is:

wrinkles

I'm a little stuck... Click here to teach me more about this clue!

'slight difficulties' is the definition.
Although both the answer and definition are plural nouns, I don't understand how they can define each other.

'romeo cracks shellfish' is the wordplay.
'romeo' becomes 'r' (phonetic alphabet: alpha, bravo, charlie etc.).
'cracks' means one lot of letters goes inside another (inserted letters go into a gap or crack).
'shellfish' becomes 'winkles'.
'r' going into 'winkles' is 'WRINKLES'.

'if' is the link.

Can you help me to learn more?

(Other definitions for wrinkles that I've seen before include "Folds, creases" , "Folds in fabric or skin" , "Signs of ageing" , "Depressions in the smoothness of skin" .)

I've seen this clue in The Independent.
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