Close! Hamilton finally involved in car crash (5)
I believe the answer is:
shunt
'car crash' is the definition.
(I've seen this before)
'close hamilton finally involved' is the wordplay.
'close' becomes 'shut' (synonyms).
'finally' says to take the final letters.
'involved' indicates putting letters inside.
The last letter of 'hamilton' is 'n'.
'shut' going around 'n' is 'SHUNT'.
'in' acts as a link.
(Other definitions for shunt that I've seen before include "Vehicle accident" , "Motor collision" , "Car crash (slang)" , "Arrange wagons; minor accident" , "Sidetrack" .)