That antifreeze is, will be very clear (10)
I believe the answer is:
noticeable
'clear' is the definition.
('noticeable' can be a synonym of 'clear')
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for noticeable that I've seen before include "impressive" , "Easily seen; clear" , "plain" , "Capable of being detected" , "Conspicuous" .)