Without love, Oedipus complex may be an advantage (6)
I believe the answer is:
upside
'an advantage' is the definition.
(both can mean a positive aspect of something)
'without love oedipus complex' is the wordplay.
'without' suggests deleting specific letters.
'love' becomes 'o' (love means zero in tennis).
'complex' indicates anagramming the letters.
'oedipus' with 'o' removed is 'edipus'.
'edipus' with letters rearranged gives 'UPSIDE'.
'may be' is the link.
(Other definitions for upside that I've seen before include "Favourable aspect" , "Positive aspect of a situation" , "Top surface of something" , "advantage" .)