Artillery bombardment (9)
(Other definitions for cannonade that I've seen before include "Period of continuous heavy gunfire" , "Barrage" , "attack" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">artillery bombardment</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for shellfire that I've seen before include "Act of war" , "What generates multiple reports" , "use of artillery" , "Barrage" , "Bombardment from heavy artillery" .)