Precipitance (5)
I believe the answer is:
haste
'precipitance' 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 "Excessive speed or urgency" , "''More . . . . ., less speed'' (5)" , "Possible cause of careless mistakes?" , "Overly eager speed" , "Rushing (but with less speed?)" .)