Smoothly, uniformly (6)
I believe the answer is:
evenly
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">smoothly</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">uniformly</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for evenly that I've seen before include "On an equal basis" , "In measured and level way" , "not getting ruffled" , "Smoothly or fairly" , "In level or uniform manner" .)