The works outing in one? (7)
I believe the answer is:
omnibus
'one?' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for omnibus that I've seen before include "collection of novels?" , "Several books in one" , "One can expect to be moved by this" , "public service" , "Collection of writings" .)