Common fertilizer (7)
I believe the answer is:
nitrate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">common fertilizer</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nitrate that I've seen before include "salt" , "Natural or synthetic fertiliser" , "Nattier (anag.)" , "Fertiliser chemical" , "following 28 [SILVER]" .)