Poor sci-fi, after editing? Dull (9)
I believe the answer is:
soporific
'dull' is the definition.
(similar in meaning)
'poor sci-fi after editing?' is the wordplay.
'after editing?' indicates an anagram.
'poor'+'sci'+'fi'='poorscifi'
'poorscifi' with letters rearranged gives 'SOPORIFIC'.
(Other definitions for soporific that I've seen before include "Causing sleepiness" , "Sedative" , "Sleep-inducing" , "Inducing mental lethargy" , "making one nod" .)