Socialist paper that - according to Spooner - doesn't get Keir Starmer? (3,3)
I believe the answer is:
red rag
'socialist paper that according to spooner doesn't get keir starmer?' is the definition.
The definition suggests a singular noun which matches the answer.
'socialist paper' is the wordplay.
'socialist' becomes 'red' (socialism is often associated with the colour red).
'paper' becomes 'rag' (rag is a kind of paper).
'red'+'rag'='RED RAG'
(Other definitions for red rag that I've seen before include "might attract a charge" , "Gerard (anag) - cause of infuriation" , "Reputed to annoy bull" , "It is offensive to a bull" , "Source of extreme provocation" .)