Greek character having high tea (3)
I believe the answer is:
eta
'greek character' is the definition.
(letter from the Greek alphabet)
'high tea' is the wordplay.
'high' indicates an anagram (can mean drunk or on drugs and hence disordered).
'tea' with letters rearranged gives 'ETA'.
'having' is the link.
(Other definitions for eta that I've seen before include "Basque separatist movement" , "Militant Basque organisation - Greek letter" , "Greek letter E; estimated time of arrival (abbr.)" , "Foreign letter" , "letter from Greece?" .)