The girl and the writer to run away together (8)
I believe the answer is:
penelope
'the girl' is the definition.
'the writer to run away together' is the wordplay.
'the writer' becomes 'pen' (something which writes).
'to run away together' becomes 'elope' (I've seen this in another clue).
'pen'+'elope'='PENELOPE'
'and' acts as a link.
(Other definitions for penelope that I've seen before include "Ulysses' faithful wife" , "Woman" , "Wife of Odysseus or Ulysses" , "Odysseus's wife" , "girl" .)