Bluish hue (4)
I believe the answer is:
aqua
'bluish hue' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aqua that I've seen before include "Latin for water" , "Water; pale blue colour" , "-- fortis, 'strong water'" , "Hue" , "(Denoting) water (Lat)" .)