Run off with Penelope, abandoning writer (5)
I believe the answer is:
elope
'run off' is the definition.
(I know that run off can be written as elope)
'penelope abandoning writer' is the wordplay.
'abandoning' is a deletion indicator.
'writer' becomes 'pen' (something which writes).
'penelope' with 'pen' removed is 'ELOPE'.
'with' is the link.
(Other definitions for elope that I've seen before include "Bolt" , "escape" , "leave with lover" , "Run away to get married" , "Run away with lover" .)