Reference work one on China so complex? (7)
I believe the answer is:
oedipal
'complex?' is the definition.
(Oedipal complex is an example)
'reference work one on china' is the wordplay.
'reference work' becomes 'OED'.
'one' becomes 'I' (Roman numeral).
'on' says to put letters next to each other.
'china' becomes 'pal' (I've seen this before).
'oed'+'i'+'pal'='OEDIPAL'
'so' is the link.
(Other definitions for oedipal that I've seen before include "Relating to a son/mother complex" , "Type of complex" , "type of conflict arising in Greece" , "Of legendary king of Thebes" , "Like a boy desiring his mother" .)