Excessive speed (5)
I believe the answer is:
haste
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">excessive 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 haste that I've seen before include "Urgent hurry" , "''Marry in . . . . ., repent at leisure''" , "Rush; urgency" , "Undue speed" , "furious activity" .)