Aquarium accessory (7)
I believe the answer is:
aerator
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">aquarium accessory</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for aerator that I've seen before include "It provides the fizz" , "Device for pumping in air" , "One may emit much gas" , "Device such as used in tropical fish tanks" , "Maybe fork" .)