Score with gangsters in Chicago and Oklahoma (8)
I believe the answer is:
musicals
'chicago and oklahoma' is the definition.
I can't tell whether this defines the answer.
'score with gangsters' is the wordplay.
'score' becomes 'musical' ('musical score' can be a synonym of 'score').
'with' says to put letters next to each other.
'gangsters' becomes 's' (I am not sure about this - if you are sure you should believe this answer much more).
'musical'+'s'='MUSICALS'
'in' is the link.
Can you help me to learn more?
(Other definitions for musicals that I've seen before include "'South Pacific and Carousel, say (8)'" , "Hair and Grease" , "Stage shows with songs and dance" .)