Take the polish off one's car in a crash (7)

I believe the answer is:

coarsen

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

'take the polish off' is the definition.
I can't judge whether this defines the answer.

'one's car in a crash' is the wordplay.
'in a crash' indicates an anagram.
'ones'+'car'='onescar'
'onescar' with letters rearranged gives 'COARSEN'.

Can you help me to learn more?

(Other definitions for coarsen that I've seen before include "become inferior" , "Make rougher" , "Make more harsh" , "Become rough or insensitive" , "Turn rough" .)

I've seen this clue in The Irish Independent.

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