Maybe I’m gone on her! (6)
I believe the answer is:
imogen
'her' is the definition.
(I've seen this before)
'maybe i'm gone on' is the wordplay.
'maybe' is an anagram indicator.
'on' says to put letters next to each other.
'im' after 'gone' is 'goneim'.
'goneim' is an anagram of 'IMOGEN'.
(Other definitions for imogen that I've seen before include "girl" , "identity of Cymbeline's daughter" , "Woman" , "child of a king" , "Princess in "Cymbeline"" .)