Clue: Susan Coolidge's girl learned cricket in US (7)
Answer: KATYDID
Explanation: Definition: cricket in US
A charade of KATY ('Susan Coolidge's girl'; Susan Coolidge was the pen name of the author of a series of books starting with *What Katy Did*) plus DID (from the book title or, rather loosely, 'learned'). A katydid is an insect cricket, named for its stridulating call.