Matey role for which Nero had no love (7)
I believe the answer is:
partner
'matey' is the definition.
'role for which nero had no love' is the wordplay.
'role' becomes 'part' ('part' can be a synonym of 'role').
'for which' is a charade indicator (letters next to each other).
'had no' indicates named letters should be taken away.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'nero' with 'o' taken away is 'ner'.
'part'+'ner'='PARTNER'
(Other definitions for partner that I've seen before include "Associate, in business or private life" , "Colleague, bedfellow" , "teammate" , "Mate or business associate" , "south to north, perhaps" .)