Nothing by writer accessible? (4)
I believe the answer is:
open
'accessible?' is the definition.
(thesaurus)
'nothing by writer' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'by' says to put letters next to each other.
'writer' becomes 'pen' (I've seen this before).
'o'+'pen'='OPEN'
(Other definitions for open that I've seen before include "Not closed or obstructed" , "Accessible - candid" , "Start - frank" , "Allowing entry and exit" , "Not yet decided - to start" .)