First, second or reverse (4)
I believe the answer is:
gear
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">first second or reverse</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for gear that I've seen before include "Toothed wheel and youthful fashion" , "Clothing - tackle" , "Equipment - changed in the car?" , "Illicit drugs (slang) - kit" , "Cogwheel - equipment" .)