With all possible speed (7)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">with all possible speed</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for hotfoot that I've seen before include "Without the slightest delay" , "acting quickly?" , "With all possible speed" , "flat out" , "Experienced by firewalker" .)
(Other definitions for posthaste that I've seen before include "As quickly as possible" , "at the double" , "With utmost speed -- to the pass (anag)" , "Speedily" , "Hurry the mail with utmost speed" .)