- Able to make heads or tails
- Accidents will happen
- Ace up one’s sleeve
- Achille’s heel
- Act in cold blood
- Ad infinitum
- Add insult to injury
- After one’s own heart
- Again and again
- Alive and kicking
- All hope abandon ye who enter here
- All in a days work
- All things considered
- All things to all men
- All through the ages
- Almighty dollar
- Alpha and omega
- Ample opportunity
- Any port in a storm
- Apple of one’s eye
- Armed to the teeth
- As a matter of fact
- As every schoolboy knows
- As far as that goes
- At beck and call
- At death’s door
- At long last
- At one’s earliest convenience
- At one’s wits’ end
- At the cross-roads
- Axe to grind
- My brother’s keeper