(right) up (one's) alley
Ideally suited to one's interests. Anna loves watching movies, so I'm sure she'll go to the film festival with you—that's right up her alley.
up (one's) alley
Suited to one's interests. I really like Romantic poetry, so this class on John Keats is right up my alley. I'm sure Dave can fix your car—mechanical things like that are really up his alley.
up one's alley
see under right up one's alley.
right up one's alley, to be
To be in one’s particular specialty or to one’s precise taste. The word alley has long been used for one’s special province; Francis Bacon so used it in his essay Of Cunning (1612): “Such men . . . are good but in their own Alley.” Up one’s alley, however, is a twentieth-century turn of phrase. Margaret Carpenter used it in her novel Experiment Perilous (1943): “It isn’t up my alley at all.” See also not my cup of tea.