Excessive urgency (5)
I believe the answer is:
haste
'excessive urgency' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for haste that I've seen before include "Speed, hurry" , "Possible cause of careless mistakes?" , "Leader abandons modest" , "The more of it, the less speed sometimes" , "Urgency of action" .)