Gunpowder constituent (9)
(Other definitions for saltpetre that I've seen before include "chemical" , "Gunpowder ingredient" , "Explosive ingredient" , "explosive component" , "Potassium nitrate" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">gunpowder constituent</span>' is the definition.<br/ ><span class="explanation-format__explanation">(gunpowder contains nitre)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for nitre that I've seen before include "fertiliser" , "safeguard against decay" , "Also known as salt-petre" , "A part of fertilizer" , "what goes into bangers" .)