right up one's alley - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Also, right down one's alley. In one's specialty, to one's taste, as in Writing press releases is right up her alley, or He loved opera, so this program of arias was right down his alley. These idioms use alley in the sense of “one's own province,” a usage dating from the early 1600s. [First half of 1900s] Also see cup of tea.