The Trump color for the round is Blue and the required color is White.
The played cards are: 6 White, 7 White, 11 Red and a 3 White.
The last player would like to play the 1 Blue Feather and win the Trick (because the Blue color is the Trump color for the Round), but he can't, because there is a White Feather card in the peacock's tail still - the 2 White Feather.
The last player is forced to play the 2 White Feather card and the Trick is won by the 7 White Feather.