Susan Coolidge's girl learned cricket in US (7)
I believe the answer is:
katydid
'cricket in us' is the definition.
(type of cricket found in the US)
'susan coolidge's girl learned' is the wordplay.
'susan coolidge's girl' becomes 'Katy' (character from What Katy Did by Susan Coolidge).
'learned' becomes 'did' (do can mean to learn about or study something).
'katy'+'did'='KATYDID'
(Other definitions for katydid that I've seen before include "American grasshopper" , "insect" , "US bush cricket" , "Large cricket" , "American bush cricket" .)