Frantic use of stimulant before the end of deadline (4-6)
I believe the answer is:
last-minute
'frantic' is the definition.
(both can mean rushed or hurried)
'use of stimulant before the end of deadline' is the wordplay.
'use of' indicates anagramming the letters.
'before' says to put letters next to each other.
'the end of' suggests the final letters.
The last letter of 'deadline' is 'e'.
'stimulant' is an anagram of 'lastminut'.
'lastminut'+'e'='LAST-MINUTE'
(Other definitions for last-minute that I've seen before include "Done at the final moment" , "Eleventh hour" , "Done at the latest possible moment" , "very late" , "Eleventh-hour" .)