Tragic end to a foolishly hasty accident (5)
I believe the answer is:
crash
'accident' is the definition.
(I know that crash is a type of accident)
'tragic end to a foolishly hasty' is the wordplay.
'end' suggests the final letters.
'to a foolishly hasty' becomes 'rash' (I am not sure about this - if you are sure you should believe this answer much more).
The last letter of 'tragic' is 'c'.
'c'+'rash'='CRASH'
Can you help me to learn more?
(Other definitions for crash that I've seen before include "failure" , "Impact" , "Planned quickly for emergency" , "Disastrous market fall" , "Car accident" .)