I'd moved away from crash, possibly grave if not acute (6)
I believe the answer is:
accent
'acute' is the definition.
(I've seen this before)
'i'd moved away from crash possibly grave if not' is the wordplay.
I cannot quite understand how this works, but
'away' could be 'a' (abbreviation as used in sports fixtures) and 'a' is found within the answer.
'not' could be 'nt' (synonyms) and 'nt' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for accent that I've seen before include "Regional speech characteristic" , "Local way of speaking or enunciation" , "Grave, perhaps" , "Emphasise" , "intensity" .)