Progressive (2-5)
I believe the answer is:
go-ahead
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">progressive</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for go-ahead that I've seen before include "Enterprising" , "Enterprisingly progressive" , "Permission to proceed" , "Up-and-coming - authorisation" , "Pioneering (green light?)" .)