Protuberance, swelling (5)
I believe the answer is:
bulge
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">protuberance</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">swelling</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that swelling can be written as bulge)</span><br/ ><br/ ></span>
(Other definitions for bulge that I've seen before include "Hump" , "Swelling - sudden increase" , "Protrude" , "Swell" , "Rounded swelling" .)