Drive too fast (5)
I believe the answer is:
speed
'drive too fast' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for speed that I've seen before include "Tempo - drug" , "Rate of movement" , "Move quickly (and illegally?)" , "Rapidity of movement" , "'More haste, less . . . . .'" .)