Pronounced lines in fruit (7)
I believe the answer is:
rosehip
'fruit' is the definition.
(fruit of a rose plant)
'pronounced lines in' is the wordplay.
'pronounced lines' becomes 'rose' (I can't explain this - if you can you should believe this answer much more).
'in' becomes 'hip' (both can mean fashionable).
'rose'+'hip'='ROSEHIP'
Can you help me to learn more?
(Other definitions for rosehip that I've seen before include "Fruit of a popular flower" , "Fruit of the brier" , "Fruit on wild plant" , "Part of plant" , "Fruit of the briar" .)