Not good enough? That's unfortunate (3,3)
I believe the answer is:
too bad
This could be a double definition.
'not good enough?' is the first definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I don't see?
'unfortunate' is the second definition.
(similar in meaning)
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for too bad that I've seen before include "A pity, being excessively naughty" , "Informally regrettable, a pity" , "Tough" , "I have no sympathy" , "Informally regrettable - excessively wicked" .)