Dictionary is holding up returning name of complex (7)
I believe the answer is:
oedipus
'name of complex' is the definition.
'Oedipus' can be an answer for 'complex' (Oedipus complex is an example). I'm unsure of the 'name of' bit.
'dictionary is holding up returning' is the wordplay.
'dictionary' becomes 'OED' (Oxford English Dictionary).
'holding' means one lot of letters goes inside another.
'returning' says the letters should be written in reverse.
'up' reversed gives 'pu'.
'is' going around 'pu' is 'ipus'.
'oed'+'ipus'='OEDIPUS'
Can you help me to learn more?
(Other definitions for oedipus that I've seen before include "Old Greek king who killed his father and married his mother" , "Theban king of legend" , "Mythical Greek king of Thebes" , "Legendary Greek king with mother complex" , "One who married his mother" .)