(literally) With a single blow, effort, or act.
(figuratively, by extension) At once, immediately; in an instant.
Source: en.wiktionary.orgHere am I at one stroke incestuous, adulteress, sodomite, and all that in a girl who only lost her maidenhead today What progress, my friends... with what rapidity I advance along the thorny road of vice. Marquis de Sade
An oak is not felled at one stroke. Spanish Proverb
A tree is not felled at one stroke. Hungarian Proverb