Start with nothing to write on (4)
I believe the answer is:
open
'start' is the definition.
(opening is a kind of starting)
'nothing to write on' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'to write' becomes 'pen' ('pen' can be a synonym of 'write').
'on' is a charade indicator (letters next to each other).
'o'+'pen'='OPEN'
'with' is the link.
(Other definitions for open that I've seen before include "Unenclosed" , "Not yet decided - to start" , "Traditional room heater" , "Start - frank" , "Undo; exposed to attack" .)