Put on new coat with narrow back, keeping trendy (7)
I believe the answer is:
repaint
'put on new coat' is the definition.
(I've seen this before)
'narrow back keeping trendy' is the wordplay.
I cannot quite understand how this works, but
'trendy' could be 'in' ('in' can mean fashionable) and 'in' is found within the answer.
The remaining letters 'repat' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'with' is the link.
Can you help me to learn more?
(Other definitions for repaint that I've seen before include "put on another coat" , "put on new coat" , "To provide fresh cover" .)