Magazine directors finding backing for paper (9)
I believe the answer is:
clipboard
'backing for paper' is the definition.
(paper might be pinned to a clipboard)
'magazine directors' is the wordplay.
'magazine' becomes 'clip' (clip can mean a magazine of ammunition in a gun).
'directors' becomes 'board' (I've seen this before).
'clip'+'board'='CLIPBOARD'
'finding' is the link.
(Other definitions for clipboard that I've seen before include "What may lie behind writing" , "text-copying facility" .)