something used in an attempt, often inadequate, to hide embarrassment or shame
—The pitcher lost the game, 10-3, but his home run in the ninth inning provided him a fig leaf of sorts.

Satan came in the form of a serpent and visited Adam and Eve while they were living in the Garden of Eden. He tempted Eve to eat the fruit of the tree of the knowledge of good and evil. She ate it, and gave some to Adam, who ate it also, causing them to lose their innocence:

When the woman saw that the tree produced fruit that was good for food, was attractive to the eye, and was desirable for making one wise, she took some of its fruit and ate it. She also gave some of it to her husband who was with her, and he ate it. Then the eyes of both of them opened, and they knew they were naked; so they sewed fig leaves together and made coverings for themselves. (Genesis 3:6,7)

Following this disobedience, Adam and Eve tried to hide their nakedness by making clothing from fig leaves, and then they tried to hid from God. But God knew what they had done. Because of their sin, he expelled them from the Garden of Eden forever.