Waste time: too hasty (5)
I believe the answer is:
trash
'waste' is the definition.
(I know that waste can be written as trash)
'time too hasty' is the wordplay.
'time' becomes 't' (abbreviation).
'too hasty' becomes 'rash' (I've seen this in another clue).
't'+'rash'='TRASH'
(Other definitions for trash that I've seen before include "Rubbish, litter" , "pulp" , "bunk" , "Refuse; wreck" , "Wreck; rubbish" .)