Complex character first seen in pseudo complex (7)
I believe the answer is:
oedipus
'complex character' is the definition.
(I've seen this before)
'first seen in pseudo complex' is the wordplay.
'first' becomes 'i' (Roman numeral for one or first).
'seen in' indicates putting letters inside.
'complex' is an anagram indicator.
'pseudo' with letters rearranged gives 'oedpus'.
'i' going inside 'oedpus' is 'OEDIPUS'.
(Other definitions for oedipus that I've seen before include "Old Greek king who killed his father and married his mother" , "He solved Sphinx's riddle" , "who had parental problems" , "King known for complex" , "Mythological king who killed his father and married his mother" .)