Butchers laugh terribly about butchery (9)
I believe the answer is:
slaughter
'butchery' is the definition.
(I know that butchery can be written as slaughter)
'butchers laugh terribly about' is the wordplay.
'about' says the answer is hidden in the clue (the clue goes around or about the answer).
'SLAUGHTER' is hidden within 'butchers laugh terribly'.
(Other definitions for slaughter that I've seen before include "Glare thus to cause bloodthirsty killing" , "Murder" , "in which many die" , "Killing (of farm animals)" , "Butcher" .)