Clever, but coming to a grisly end (3)
I believe the answer is:
sly
'clever' is the definition.
(thesaurus)
'coming to a grisly end' is the wordplay.
'coming to' becomes 'sl' (I can't explain this - if you can you should believe this answer much more).
'end' suggests the final letters.
The last letter of 'grisly' is 'y'.
'sl'+'y'='SLY'
'but' is the link.
Can you help me to learn more?
(Other definitions for sly that I've seen before include "Crafty, devious" , "'Cunning, wily (3)'" , "Cunning, deceitful" , "Cunning; surreptitious" , "Devious and furtive" .)