Color close to aqua (4)
I believe the answer is:
teal
'color close to aqua' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for teal that I've seen before include "Bluish shade of green" , "Raise (subject matter)" , "Duck; greenish-blue colour" , "Dark green-blue; duck" , "Duck - dark greenish-blue" .)