Ambition (5)
I believe the answer is:
drive
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ambition</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that ambition can be written as drive)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for drive that I've seen before include "gear" , "tenacity" , "Impetus; take car" , "Urge; approach to house" , "Control and steer vehicle" .)