Giant visibly very different from Cyclops! (5)

I believe the answer is:

argus

I'm a little stuck... Click here to teach me more about this clue!

'giant' is the definition.
(Argus is an example)

I cannot understand how the rest of the clue works.

(Other definitions for argus that I've seen before include "In Greek myth, a many-eyed monster slain by Hermes" , "Hundred-eyed giant in mythology" , "Giant with one hundred eyes in Greek mythology" , "Alert watchman" , "Monster with many eyes slain by Hermes in Greek myth" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.