Maybe she's supporting sister without love (7)
I believe the answer is:
pronoun
'maybe she's' is the definition.
('she' is a pronoun)
'supporting sister without love' is the wordplay.
'supporting' becomes 'pro' (I've seen this in another clue).
'sister' becomes 'nun' (sister is a term of address for a nun).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'love' becomes 'o' (love means zero in tennis).
'nun' placed around 'o' is 'noun'.
'pro'+'noun'='PRONOUN'
(Other definitions for pronoun that I've seen before include "Part of speech" , ""She" or "him", for example" , "He is one" , "Possibly he" , "Word like I or she" .)