Reprimand; plant (6)
I believe the answer is:
rocket
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">reprimand</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">plant</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(rocket is a kind of plant)</span><br/ ><br/ ></span>
(Other definitions for rocket that I've seen before include "Salad plant - shoot up" , "Go up very quickly" , "Firework and lettuce" , "Salad plant; missile" , "High speed steam engine (1829)" .)