Some terrific stories in circulation (3-2)
I believe the answer is:
sci-fi
This might be a double definition.
'some terrific stories in' is the first definition.
The definition suggests a singular noun which matches the answer.
'circulation' is the second definition.
Both the answer and definition are singular nouns.
Maybe they are linked in a way I don't understand?
(Other definitions for sci-fi that I've seen before include "Literary genre (abbrev)" , "Space opera genre" , "Sort of book" , "Fantasy genre based in the future" , "SF" .)