There's nothing sinful about her (5)
I believe the answer is:
olive
'her' is the definition.
'there's nothing sinful about' is the wordplay.
'there's nothing' becomes 'o' (I've seen this in other clues).
'sinful' becomes 'evil' (I've seen this before).
'about' is a reversal indicator.
'evil' reversed gives 'live'.
'o'+'live'='OLIVE'
(Other definitions for olive that I've seen before include "shades of green" , "Evergreen Mediterranean tree" , "Yellowish-green colour" , "This branch is offered in peace gesture" , "It's branch is a symbol of peace" .)