Greek king, complex for psychiatrists (7)
I believe the answer is:
oedipus
'greek' is the definition.
(I have seen 'Complex Greek ' mean 'oedipus' so perhaps 'greek' could also mean 'oedipus')
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for oedipus that I've seen before include "Theban king of legend" , "One who married his mother" , "He married his mother (and had a Freudian complex!)" , "Complex man" , "Mythical Greek king of Thebes" .)