Reckless speed (5)
I believe the answer is:
haste
'reckless speed' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for haste that I've seen before include "The more of it, the less speed, it is said" , "Speed, hurry" , "Excessive speed or urgency" , "Inconsiderate speed" , "Speediness or rush" .)