The high cost of terrorism? (4)
I believe the answer is:
bomb
This could be a double definition.
'the high' is the first definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
'cost of terrorism?' is the second definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
Can you help me to learn more?
(Other definitions for bomb that I've seen before include "One set off" , "Great deal of money (slang)" , "Mine" , "See 18" , "Explosive device" .)