Upset? You'll get over it (5)
I believe the answer is:
cross
'upset?' is the definition.
(I've seen this in another clue)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for cross that I've seen before include "Put out" , "X" , "Rood - intersect - annoyed" , "something to bear" , "frustrated?" .)