Speak unprepared (2-3)
I believe the answer is:
ad-lib
'speak unprepared' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ad-lib that I've seen before include "Unprepared remark" , "Off the cuff remark" , "Unscripted impromptu remark" , "Improvised remark" , "Speak off the cuff" .)