Check, curb (4)
I believe the answer is:
stem
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">check</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(both can mean to control or stop)</span><br/ ><br/ >'<span class="explanation-format__original">curb</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for stem that I've seen before include "race" , "supporter of flag, for example" , "Originate (from)" , "Stalk; restrict (a flow)" , "Main stalk of a plant" .)