Abstemious Greek character upset after fit of rage (9)
I believe the answer is:
temperate
'abstemious' is the definition.
(similar in meaning)
'greek character upset after fit of rage' is the wordplay.
'greek character' becomes 'eta' (letter from the Greek alphabet).
'upset' says the letters should be written backwards.
'after' means one lot of letters go next to another.
'fit of rage' becomes 'temper' (temper can mean an angry fit).
'eta' in reverse letter order is 'ate'.
'ate' put after 'temper' is 'TEMPERATE'.
(Other definitions for temperate that I've seen before include "Showing self-restraint" , "comfortably warm?" , "It is reasonable" , "With mild climate" , "Continent" .)