The initial idioms of the letter A

a Bronx cheer	brony
a bucks party	a bully pulpit
a bum rap	a bum steer
a bumpy ride	a bunch of baloney
a bunch of malarkey	a bundle of joy
a burnt child dreads the fire	a busman's holiday
a buzz word	a call girl
a calling card	a camel is a horse designed by a committee
a camel's nose (under the tent)	a camp follower
a can of worms	a capful of wind
a carbon copy	a carrot and stick
a carrot-top	a case in point
a cash cow	a cat may look at a king
a cat nap	a cattle market
a cause célêbre	to some degree