Fill with air (7)
I believe the answer is:
inflate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fill with air</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for inflate that I've seen before include "Enlarge" , "Distend" , "Puff up" , "Dilate" , "Exaggerate or fill with air" .)