Lines (up) (6)
I believe the answer is:
queues
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lines up</span>' is the definition.<br/ ><span class="explanation-format__explanation">('queue' can be a synonym of 'line up')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for queues that I've seen before include "Lines of waiting people or vehicles" , "Lines of waiters" , "Waits in line" , "lots of waiters" , "Line of waiting people or vehicles" .)