Keith Morrow Martin (1911 - 1983, American) costume design ofor "Can Can The Bat", dated 1937, likely from "Show Piece" (a 1937 ballet; possibly for the 1936 ballet Harlequin for President?). The watercolor measures 14" x 11". You can see mat burn at the very edges of the paper and some corners are bent / bruised. The work is likely executed in pencil, with watercolor and gouache (like the red top of the costume looks denser then watercolor, so I assume gouache).
MoMA holds in their collection 15 costume designs by KMM. Nine of the works are for a 1936 ballet called "Harlequin for President", while 6 are for the 1937 ballet "Show Piece". This being dated 1937 I am guessing it relates to the "Show Piece" costumes. You can look for yourself with a simple google search.
It is inscribed lower left "For Harry Smith / Keith Martin/ 1937" and titled lower right "Can-Can / the Bat". Harry Smith MAY be the famed stage writer, but he died in 1936, so the dates don't quite line up.
Reverse of paper with some tape marks. "B6" (?) in pencil lower left below signature and inscription. Lots of "movement" in the visible pencil lines in the sketch.
Happy to answer any questions you may have. Need additional photos? Let me know specifically what you want to see and I'll make it happen.