The brightest star in the constellation Aquila (6)
I believe the answer is:
altair
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">the brightest star in the constellation aquila</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 altair that I've seen before include "Bright star in Aquila" , "Member of Eagle family" , "Heavenly body" , "First-magnitude star" , "Bright star; lariat (anag.)" .)