Rising agent (5)
I believe the answer is:
yeast
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rising agent</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for yeast that I've seen before include "Fungi used in bakery" , "Baker's raising agent" , "Rising agent" , "Fungus used in fermenting" , "Agent for making bread" .)