In a state of ire, she's so upset! (5)
I believe the answer is:
rosie
'in a state' is the definition.
I can't judge whether this definition defines the answer.
'ire she's so upset' is the wordplay.
I cannot quite see how this works, but
'so upset' could be 'os' (I've seen this in other clues) and 'os' is present in the answer.
an anagram of 'ire' is 'rie' which is located in the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for rosie that I've seen before include "Female" , "It could be tea" , "-- Lee is slang for tea" , "Girl's name" , "literary drinking companion" .)