[at one stroke] See: [AT A BLOW] or [AT ONE STROKE].

[at one time] {adv. phr.} 1. In the same moment; together. […]

[at one's beck and call] or [at the beck and call […]

[at one's best] {prep. phr.} In best form; displaying one's best […]

[at one's door] or [at one's doorstep] {adv. phr.} 1. Very […]

[at one's ease] See: [AT EASE] (2).

[at one's elbow] {adv. phr.} Close beside you; nearby. * /The […]

[at one's feet] {adv. phr.} Under your influence or power. * […]

[at one's fingertips] {adv. phr.} 1. Within easy reach; quickly touched; […]

[at one's heels] {adv. phr.} Close behind; as a constant follower […]