As car crashes, almost remain sardonic (9)
I believe the answer is:
sarcastic
'sardonic' is the definition.
(similar in meaning)
'as car crashes almost' is the wordplay.
'crashes' indicates an anagram.
'almost' becomes 'stic' (I can't explain this - if you can you should believe this answer much more).
'as'+'car'='ascar'
'ascar' anagrammed gives 'sarca'.
'sarca'+'stic'='SARCASTIC'
'remain' acts as a link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for sarcastic that I've seen before include "Mockingly ironic" , "Using mocking wit" , "Expressing ridicule, contempt, maybe irony" , "Using biting irony" , "Derisive" .)