Terrible danger with opening of explosive bomb (7)
I believe the answer is:
grenade
'bomb' is the definition.
(grenade is a kind of bomb)
'terrible danger with opening of explosive' is the wordplay.
'terrible' indicates anagramming the letters.
'with' means one lot of letters goes inside another.
'opening of' suggests taking the first letters.
The initial letter of 'explosive' is 'e'.
'danger' anagrammed gives 'grnade'.
'grnade' enclosing 'e' is 'GRENADE'.
(Other definitions for grenade that I've seen before include "Missile thrown" , "Hand-thrown explosive" , "Angered (anag)" , "Small explosive device" , "Handy bomb" .)