Element of munitions disrupted her plans (8)
I believe the answer is:
shrapnel
'element of munitions' is the definition.
(shrapnel means bits of a bomb)
'disrupted her plans' is the wordplay.
'disrupted' indicates an anagram.
'her'+'plans'='herplans'
'herplans' anagrammed gives 'SHRAPNEL'.
(Other definitions for shrapnel that I've seen before include "Dangerous fragments" , "Flying debris" , "Metal from exploding artillery shell" , "Bomb or shell fragments" , "Fragments from exploded shell" .)