Newspaper in stew when not published! (3)
I believe the answer is:
rag
'newspaper' is the definition.
(informal term for a newspaper)
'stew when not published' is the wordplay.
'stew' becomes 'ragout' (ragout is a kind of stew).
'when not' indicates named letters should be taken away.
'published' becomes 'out' (a published book is 'out').
'ragout' with 'out' removed is 'RAG'.
'in' is the link.
(Other definitions for rag that I've seen before include "Torn cloth or despised newspaper" , "A tattered cloth or university frolic" , "charity event" , "Cheap newspaper" , "Practical joke" .)