It might bring down the house (3)
I believe the answer is:
tnt
'it might bring down the house' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tnt that I've seen before include "Very powerful explosive, compressed" , "Explosive stuff" , "Type of high explosive" , "Initially, powerful explosive" , "Explosive compound" .)