Undue hurry (5)
I believe the answer is:
haste
'undue hurry' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for haste that I've seen before include "Urgent hurry" , "Over-eager speed" , "Rapidity" , "Heats (anag.)" , "More of this can slow you up!" .)