The German’s upset and unhappy (3)
I believe the answer is:
sad
'unhappy' is the definition.
('sad' is associated in meaning with 'unhappy')
'the german's upset' is the wordplay.
'the german' becomes 'das' ('the' in German).
'upset' is a reversal indicator.
'das' backwards is 'SAD'.
'and' acts as a link.
(Other definitions for sad that I've seen before include "Mournful - sorry" , "Tragic" , "Morose" , "Unhappy or melancholy" , "Miserable" .)