A shade unhappy? Toughen up! (5,4)
I believe the answer is:
steel blue
'a shade' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'unhappy? toughen up' is the wordplay.
I cannot quite see how this works, but
'unhappy?' could be 'blue' (blue can mean sad or miserable) and 'blue' is found in the answer.
'toughen' could be 'steel' (I've seen this in another clue) and 'steel' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for steel blue that I've seen before include "metallic colour" , "Metallic tone" .)