Chromium remains in accident (5)
I believe the answer is:
crash
'accident' is the definition.
(crash is a kind of accident)
'chromium remains' is the wordplay.
'chromium' becomes 'Cr' (chemical symbol).
'remains' becomes 'ash' (remains of a fire).
'cr'+'ash'='CRASH'
'in' is the link.
(Other definitions for crash that I've seen before include "Car accident" , "Planned quickly for emergency" , "Impact" , "Bang" , "Disastrous market fall" .)