Recognised young athlete as somewhat unhappy? (4-4)

I believe the answer is:

half-blue

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

'somewhat unhappy?' is the definition.
I can't judge whether this definition defines the answer.

'recognised young athlete' is the wordplay.
'recognised young' becomes 'half' (I am not sure about this - if you are sure you should believe this answer much more).
'athlete' becomes 'blue'.
'half'+'blue'='HALF-BLUE'

'as' is the link.

Can you help me to learn more?

I've seen this clue in The Independent.

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.