Roller coaster (3,6)
I believe the answer is:
big dipper
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">roller coaster</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for big dipper that I've seen before include "Amusement park attraction" , "switchback" , "Familiar US stars" , "Roller coaster - The Plough (in the US)" , "Fairground ride" .)