Carry trade is borrowing yen,

exchange yen into other currencies to buy risky assets outside Japan. Now risk is off, the whole process is reversed - those who do carry trades have to sell risky assets outside Japan, payback the yen they had borrowed, thus raising the yen exchange rate. Japanese big exporters suffer when yen exchange rate is up big, so Japan equities are sold off.

Anything related to Forex is leveraged.