Attack using half of bullets, perhaps, in case (6)
I believe the answer is:
molest
'attack' is the definition.
(thesaurus)
'half of bullets perhaps in case' is the wordplay.
'half of' means to take half the letters.
'bullets perhaps' becomes 'ammo' (I've seen this in another clue).
'in case' becomes 'lest' (eg 'lest we forget').
'ammo' with half the letters taken is 'mo'.
'mo'+'lest'='MOLEST'
'using' acts as a link.
(Other definitions for molest that I've seen before include "Pester unpleasantly" , "trouble" , "Accost or pester" , "Attack or interfere with a person" , "badger" .)