Complex character of editor, one immersed in work (7)
I believe the answer is:
oedipus
'complex character' is the definition.
(I've seen this before)
'editor one immersed in work' is the wordplay.
'editor' becomes 'ed' (abbreviation).
'one' becomes 'i' (Roman numeral).
'immersed in' indicates putting letters inside.
'work' becomes 'opus' (an opus is an artistic work).
'ed'+'i'='edi'
'edi' placed within 'opus' is 'OEDIPUS'.
'of' is the link.
(Other definitions for oedipus that I've seen before include "Greek hero - complex" , "King known for complex" , "Legendary Greek king with mother complex" , "Complex man" , "complex character" .)