This achievement/trophy is somewhat tedious. Before starting, players must find and build the parts for the new KT-4 wonder weapon. Once the KT-4 is built, use it to dissolve a blue web next to the spider's nest near Lab A (next to a perk location). This will reveal a downward slope. Slide down the slope and into a cave, where the players will have to defeat the Giant Spider boss.
Once the spider is killed, cross the crevice and go through the cave's main path. Near the exit to the surface, there will be a special Widow's Wine tap machine, where the player can drink and earn the Widow's Wine perk for free. Note that the player must have a free perk slot to drink from the machine. Drink and acquire the perk and exit the cave, where the achievement/trophy will be rewarded. Players may return to this cave to reacquire Widow's Wine if they lose it (the Giant Spider boss does not have to be defeated more than once).